Mahmoud was trying to solve the vertex cover problem on trees. The problem statement is:

Given an undirected tree consisting of *n* nodes, find the minimum number of vertices that cover all the edges. Formally, we need to find a set of vertices such that for each edge (*u*, *v*) that belongs to the tree, either *u* is in the set, or *v* is in the set, or both are in the set. Mahmoud has found the following algorithm:
 -  Root the tree at node 1. -  Count the number of nodes at an even depth. Let it be *evenCnt*. -  Count the number of nodes at an odd depth. Let it be *oddCnt*. -  The answer is the minimum between *evenCnt* and *oddCnt*. 
The depth of a node in a tree is the number of edges in the shortest path between this node and the root. The depth of the root is 0.

Ehab told Mahmoud that this algorithm is wrong, but he didn't believe because he had tested his algorithm against many trees and it worked, so Ehab asked you to find 2 trees consisting of *n* nodes. The algorithm should find an incorrect answer for the first tree and a correct answer for the second one.
The only line contains an integer *n* (2 ≤ *n* ≤ 10<sup class="upper-index">5</sup>), the number of nodes in the desired trees.
In the first sample, there is only 1 tree with 2 nodes (node 1 connected to node 2). The algorithm will produce a correct answer in it so we printed  - 1 in the first section, but notice that we printed this tree in the second section.

In the second sample:

In the first tree, the algorithm will find an answer with 4 nodes, while there exists an answer with 3 nodes like this: <img class="tex-graphics" src="https://espresso.codeforces.com/fb4efe76f0a74395fe77f22da2dbd2a3340f8b2a.png" style="max-width: 100.0%;max-height: 100.0%;"/> In the second tree, the algorithm will find an answer with 3 nodes which is correct: <img class="tex-graphics" src="https://espresso.codeforces.com/700db299c05ae94849f44b93e8240d375a0fe05f.png" style="max-width: 100.0%;max-height: 100.0%;"/>
2
-1
1 2
8
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 2
1 3
1 4
1 5
1 6
1 7
1 8
99
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
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1 40
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1 45
1 46
1 47
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1 49
1 50
1 51
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1 53
1 54
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1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
100
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
100000
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
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1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
3212
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
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1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
54321
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
54320
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
3
-1
1 2
1 3
4
-1
1 2
1 3
1 4
5
-1
1 2
1 3
1 4
1 5
6
1 2
1 3
1 4
2 5
2 6
1 2
1 3
1 4
1 5
1 6
7
1 2
1 3
1 4
2 5
2 6
1 7
1 2
1 3
1 4
1 5
1 6
1 7
67575
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
99999
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
2048
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
2047
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
2049
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
10101
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
11
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
1 10
1 11
13
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
21
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
31
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
43
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
57
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
...
73
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
...
91
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
111
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
133
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
157
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
183
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
211
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
241
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
273
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
307
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
343
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
381
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
421
1 2
1 3
1 4
2 5
2 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
1 25
1 26
1 27
1 28
1 29
1 30
1 31
1 32
1 33
1 34
1 35
1 36
1 37
1 38
1 39
1 40
1 41
1 42
1 43
1 44
1 45
1 46
1 47
1 48
1 49
1 50
1 51
1 52
1 53
1 54
1 55
1 56
1 57
1 58
1 59
1 60
1 61
1 62
1 63
1 64
1 65
1 66
1 67
1 68
1 69
1 70
1 71
1 72
1 73
1 74
1 75
1 76
1 77
1 78
1 79
1 80
1 81
1 82
1 83
1 84
1 85
1 86
1 87
1 8...
import sys
import math

MAXNUM = math.inf
MINNUM = -1 * math.inf
ASCIILOWER = 97
ASCIIUPPER = 65


def getInt():
    return int(sys.stdin.readline().rstrip())


def getInts():
    return map(int, sys.stdin.readline().rstrip().split(" "))


def getString():
    return sys.stdin.readline().rstrip()


def printOutput(a, b):
    if not a:
        sys.stdout.write(str(-1) + "\n")
    else:
        for x, y in a:
            sys.stdout.write(str(x) + " " + str(y) + "\n")

    for x, y in b:
        sys.stdout.write(str(x) + " " + str(y) + "\n")


def incorrectAlg(ln):
    ans = []
    for i in range(1, ln - 3):
        ans.append((1, i + 1))
    ans.append((1, ln - 2))
    ans.append((ln - 2, ln - 1))
    ans.append((ln - 2, ln))
    return ans


def correctAlgorithm(ln):
    ans = []
    for i in range(1, ln):
        ans.append((i, i + 1))

    return ans


def solve(ln):
    if ln < 6:
        a = None
    else:
        a = incorrectAlg(ln)
    b = correctAlgorithm(ln)
    return a, b


def readinput():
    ln = getInt()
    printOutput(*solve(ln))


readinput()
