Dasha and Stairs

最新推荐文章于 2023-04-27 00:48:42 发布

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本文介绍了一个关于计算楼梯中奇数和偶数台阶数量的编程问题。通过输入两个整数a和b来判断是否存在一个从第l到第r阶的区间，使得在这个区间内奇数和偶数台阶的数量符合输入值。

Dasha and Stairs

CodeForces - 761A

On her way to programming school tiger Dasha faced her first test — a huge staircase!

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The steps were numbered from one to infinity. As we know, tigers are very fond of all striped things, it is possible that it has something to do with their color. So on some interval of her way she calculated two values — the number of steps with even and odd numbers.

You need to check whether there is an interval of steps from the l-th to the r-th (1 ≤ l ≤ r), for which values that Dasha has found are correct.

Input

In the only line you are given two integers a,b (0 ≤ a, b ≤ 100) — the number of even and odd steps, accordingly.

Output

In the only line print "YES", if the interval of steps described above exists, and "NO" otherwise.

Example

Input

2 3

Output

YES

Input

3 1

Output

NO

Note

In the first example one of suitable intervals is from 1 to 5. The interval contains two even steps —2 and 4, and three odd:1, 3 and 5.

#include <stdio.h>
int main()
{
    int a,b;
    while(~scanf("%d %d",&a,&b))
    {
        if(!a&&!b) printf("NO\n");
        else if(a == b||a == b + 1||a == b -1) printf("YES\n");
        else printf("NO\n");
    }

    return 0;
    }