Friends Meeting

### 题目描述 在x-坐标轴（可以视为数轴）上有两个人，分别从$a$ 位置和$b$ 位置出发。 对于每个人，他可以往任意方向无限次地移动。当他第$i$ 次移动时，疲乏度增加$i$ 。例如，一个人第$1$ 次移动疲乏度增加$1$ ，第$2$ 次移动疲乏度增加$2$ （累计疲乏度为$3$ ），第$3$ 次移动增加$3$ （累计疲乏度为$6$ ），以此类推。 试求出这两个人在同一点相遇时疲乏度的和的最小值。 ### 输入格式 分两行输入两个整数$a$ 和$b$ 。 $1 \le a,b \le 1000$ 且 $ a\neq b$ 。 ### 输出格式 一个整数，即两人疲乏度的和的最小值。 ### 样例解释 - 样例1：显然，其中一个人移动一个步即可，则答案为$1$ 。 - 样例2：显然，两人各移动一步，到达位置$100$ 。答案为$1+1=2$ 。 - 样例3：为到达位置$8$ ，左边的人向右移动$3$ 步，疲乏度为$1+2+3=6$ ；右边的人向左移动$2$ 步，疲乏度为$1+2=3$ 。答案为$6+3=9$ 。 感谢@hiuseues 提供的翻译

Two friends are on the coordinate axis $ Ox $ in points with integer coordinates. One of them is in the point $ x_{1}=a $ , another one is in the point $ x_{2}=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 $ .

Print the minimum possible total tiredness if the friends meet in the same point.

3
4

1

101
99

2

5
10

9

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 $ .