Two friends are on the coordinate axis *Ox* in points with integer coordinates. One of them is in the point *x*<sub class="lower-index">1</sub> = *a*, another one is in the point *x*<sub class="lower-index">2</sub> = *b*. 

Each of the friends can move by one along the line in any direction unlimited number of times. When a friend moves, the tiredness of a friend changes according to the following rules: the first move increases the tiredness by 1, the second move increases the tiredness by 2, the third — by 3 and so on. For example, if a friend moves first to the left, then to the right (returning to the same point), and then again to the left his tiredness becomes equal to 1 + 2 + 3 = 6.

The friends want to meet in a integer point. Determine the minimum total tiredness they should gain, if they meet in the same point.
The first line contains a single integer *a* (1 ≤ *a* ≤ 1000) — the initial position of the first friend. 

The second line contains a single integer *b* (1 ≤ *b* ≤ 1000) — the initial position of the second friend.

It is guaranteed that *a* ≠ *b*.
In the first example the first friend should move by one to the right (then the meeting happens at point 4), or the second friend should move by one to the left (then the meeting happens at point 3). In both cases, the total tiredness becomes 1.

In the second example the first friend should move by one to the left, and the second friend should move by one to the right. Then they meet in the point 100, and the total tiredness becomes 1 + 1 = 2.

In the third example one of the optimal ways is the following. The first friend should move three times to the right, and the second friend — two times to the left. Thus the friends meet in the point 8, and the total tiredness becomes 1 + 2 + 3 + 1 + 2 = 9.
3
4
1
101
99
2
5
10
9
1
2
1
1
1000
250000
999
1000
1
1000
999
1
1000
1
250000
2
1
1
2
999
249001
2
998
248502
999
2
249001
998
2
248502
2
1000
249500
1000
2
249500
1
999
249500
999
1
249500
188
762
82656
596
777
8281
773
70
123904
825
729
2352
944
348
89102
352
445
2209
529
656
4096
19
315
22052
138
370
13572
546
593
576
285
242
484
773
901
4160
892
520
34782
864
179
117649
479
470
25
967
487
57840
648
106
73712
58
765
125316
235
56
8100
285
153
4422
943
13
216690
675
541
4556
4
912
206570
a = int(input())
b = int(input())
answer = 0
i = 1
c = min(a, b)
d = max(a, b)
while c != d:
    c += 1
    answer += i
    if c != d:
        d -= 1
        answer += i
    i += 1

print(answer)
