Absent-minded Masha got set of *n* cubes for her birthday.

At each of 6 faces of each cube, there is exactly one digit from 0 to 9. Masha became interested what is the largest natural *x* such she can make using her new cubes all integers from 1 to *x*.

To make a number Masha can rotate her cubes and put them in a row. After that, she looks at upper faces of cubes from left to right and reads the number.

The number can't contain leading zeros. It's not required to use all cubes to build a number.

Pay attention: Masha can't make digit 6 from digit 9 and vice-versa using cube rotations.
In first line integer *n* is given (1 ≤ *n* ≤ 3) — the number of cubes, Masha got for her birthday.

Each of next *n* lines contains 6 integers *a*<sub class="lower-index">*i*</sub><sub class="lower-index">*j*</sub> (0 ≤ *a*<sub class="lower-index">*i*</sub><sub class="lower-index">*j*</sub> ≤ 9) — number on *j*-th face of *i*-th cube.
In the first test case, Masha can build all numbers from 1 to 87, but she can't make 88 because there are no two cubes with digit 8.
3
0 1 2 3 4 5
6 7 8 9 0 1
2 3 4 5 6 7
87
3
0 1 3 5 6 8
1 2 4 5 7 8
2 3 4 6 7 9
98
3
0 1 2 3 4 5
0 1 2 3 4 5
0 1 2 3 4 5
5
3
1 2 3 7 8 9
9 8 7 1 2 3
7 9 2 3 1 8
3
1
5 2 2 5 6 7
0
1
7 6 5 8 9 0
0
1
2 5 9 6 7 9
0
1
6 3 1 9 4 9
1
1
1 9 8 3 7 8
1
2
1 7 2 0 4 3
5 2 3 6 1 0
7
2
6 0 1 7 2 9
1 3 4 6 7 0
4
2
8 6 4 1 2 0
7 8 5 3 2 1
8
2
0 8 6 2 1 3
5 2 7 1 0 9
3
2
0 9 5 7 6 2
8 6 2 7 1 4
2
3
5 0 7 6 2 1
2 7 4 6 1 9
0 2 6 1 7 5
2
3
0 6 2 9 5 4
3 8 0 1 6 9
6 9 0 1 5 2
6
3
5 6 2 9 3 5
5 4 1 5 9 8
4 4 2 0 3 5
6
3
0 1 9 1 0 8
9 9 3 5 6 2
9 3 9 9 7 3
3
3
2 5 7 4 2 7
1 5 5 9 0 3
8 2 0 1 5 1
5
1
4 6 9 8 2 7
0
1
5 3 8 0 2 6
0
1
7 9 5 0 4 6
0
1
4 0 9 6 3 1
1
1
7 9 2 5 0 4
0
1
0 7 6 3 2 4
0
1
9 8 1 6 5 7
1
1
7 3 6 9 8 1
1
1
3 9 1 7 4 5
1
1
8 6 0 9 4 2
0
1
8 2 7 4 1 0
2
1
8 3 5 4 2 9
0
1
0 8 7 1 3 2
3
1
6 2 8 5 1 3
3
1
6 0 7 5 4 8
0
1
6 2 8 4 5 1
2
1
4 3 8 9 2 3
0
1
8 1 9 2 9 7
2
1
3 7 7 6 4 2
0
1
1 4 5 7 0 5
1
2
6 6 4 7 9 0
2 1 2 8 6 4
2
2
5 3 2 9 8 2
0 7 4 8 1 8
5
2
5 7 4 2 1 9
2 2 7 1 1 8
2
2
9 3 3 6 7 2
6 2 9 1 5 9
3
2
2 0 5 7 0 8
4 5 1 5 4 9
2
2
2 6 8 1 3 1
2 1 3 8 6 7
3
2
4 3 8 6 0 1
4 7 1 8 9 0
1
2
0 2 9 1 8 5
0 7 4 3 2 5
5
2
1 7 6 9 2 5
1 6 7 0 9 2
2
2
0 2 9 8 1 7
6 7 4 3 2 5
9
2
3 6 8 9 5 0
6 7 0 8 2 3
0
2
5 1 2 3 0 8
3 6 7 4 9 2
9
2
7 8 6 1 4 5
8 6 4 3 2 5
8
2
2 3 5 1 9 6
1 6 8 7 3 9
3
2
1 7 8 6 0 9
3 2 1 7 4 9
4
2
2 4 0 3 7 6
3 2 8 7 1 5
8
2
6 5 2 7 1 3
3 7 8 1 0 9
3
2
5 8 4 7 1 2
0 8 6 2 4 9
2
2
8 0 6 5 1 4
7 1 0 8 3 4
1
2
2 3 9 1 6 7
2 5 4 3 0 6
7
3
9 4 3 0 2 6
7 0 5 3 3 9
1 0 7 4 6 7
7
3
3 8 5 1 5 5
1 5 7 2 6 9
4 3 4 8 8 9
9
3
7 7 2 5 3 2
3 0 0 6 4 4
1 2 1 1 9 1
7
3
8 1 6 8 6 8
7 0 2 5 8 4
5 2 0 3 1 9
32
3
2 7 4 0 7 1
5 5 4 9 1 4
2 1 7 5 1 7
2
3
4 4 5 0 6 6
7 1 6 9 5 4
5 0 4 0 3 9
1
3
9 4 3 3 9 3
1 0 3 4 5 3
2 9 6 2 4 1
6
3
3 8 3 5 5 5
3 0 1 6 6 3
0 4 3 7 2 4
8
3
4 1 0 8 0 2
1 5 3 5 0 7
7 7 2 7 2 2
5
3
8 1 8 2 7 1
9 1 9 9 4 7
0 0 9 0 4 0
2
3
4 6 0 3 9 2
8 6 9 0 7 2
6 9 3 2 5 7
0
3
5 1 2 9 6 4
9 0 6 4 2 8
4 6 2 8 3 7
10
3
9 3 1 8 4 6
6 9 1 2 0 7
8 9 1 5 0 3
21
3
7 1 3 0 2 4
2 4 3 0 9 5
1 9 8 0 6 5
65
3
9 4 6 2 7 0
3 7 1 9 6 4
6 1 0 8 7 2
4
3
2 7 3 6 4 5
0 2 1 9 4 8
8 6 9 5 4 0
10
3
2 6 3 7 1 0
9 1 2 4 7 6
1 4 8 7 6 2
4
3
5 4 8 1 6 7
0 9 3 5 8 6
2 4 7 8 1 3
21
3
7 2 1 3 6 9
0 3 8 4 7 6
1 4 5 8 7 0
21
3
8 6 0 5 4 9
1 8 5 3 9 7
7 4 5 1 6 8
1
1
0 1 2 3 4 5
5
3
0 1 1 2 2 3
4 5 6 7 8 9
3 4 5 6 7 8
9
2
0 1 2 3 4 5
6 7 8 9 1 2
29
3
0 1 2 3 4 5
6 7 8 9 1 2
3 4 5 6 7 8
98
3
0 1 1 2 2 3
4 5 6 7 8 9
3 4 5 6 7 1
19
2
0 1 2 3 4 5
6 7 8 9 6 6
9
2
0 1 2 3 4 5
4 5 6 7 8 9
9
2
1 8 9 1 1 0
2 3 4 5 6 7
9
2
0 1 2 3 4 5
9 8 7 6 5 4
9
3
2 3 4 5 6 7
3 4 5 6 7 8
9 1 2 3 4 5
9
3
1 1 2 3 4 5
6 7 8 9 0 2
3 4 5 6 7 8
10
3
1 1 1 0 2 3
4 5 6 7 8 9
0 0 0 0 0 0
10
3
0 1 2 2 4 5
6 7 8 9 0 1
3 3 4 5 6 7
21
3
2 0 1 3 4 5
6 7 8 9 1 1
3 4 5 6 6 7
19
3
1 1 1 1 1 1
0 2 3 4 5 6
7 8 9 2 3 4
10
2
0 1 2 3 4 5
6 6 6 7 8 9
9
3
3 4 5 6 8 9
1 1 1 1 1 1
1 2 4 5 7 0
19
def is_possible1(i, cubes):
    for cube in cubes:
        for c in cube:
            if int(c) == i:
                return True
    return False

def is_possible2(i, cubes):
    if len(cubes) < 2: return False
    for j, cube in enumerate(cubes):
        if str(i)[0] in cube:
             for k, cube2 in enumerate(cubes):
                if j != k and str(i)[1] in cube2:
                    return True
    return False

def is_possible3(i, cubes):
    if len(cubes) < 3: return False
    for j, cube in enumerate(cubes):
        if str(i)[0] in cube:
            for k, cube2 in enumerate(cubes):
                if j != k and str(i)[1] in cube2:
                    for l, cube3 in enumerate(cubes):
                        if l != j and l != k and j != k and str(i)[2] in cube3: return True
    return False


def is_possible(i, cubes):
    if len(str(i)) == 1: return is_possible1(i, cubes)
    if len(str(i)) == 2: return is_possible2(i, cubes)
    if len(str(i)) == 3: return is_possible3(i, cubes)


n = int(input())

cubes = []
for i in range(n):
    cubes.append(input().split())

flat_cubes = [c for cube in cubes for c in cube]
if '1' not in flat_cubes:
    print(0)
else:
    i = 1
    while is_possible(i, cubes):
        i += 1
    print(i-1)

 	  		  		 	 			   	 									