Dasha and Stairs

最新推荐文章于 2019-01-08 21:35:36 发布

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本题是一道关于模拟的编程题目，需要验证给定的奇数和偶数步数是否能在连续的楼梯区间中找到匹配的情况。通过判断奇数与偶数步数之间的差值来确定是否存在符合条件的区间。

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

$\text{[math]}$

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.

Examples

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.

解题说明：此题是一道模拟题，给定奇数偶数个数,很显然，奇偶数相差必须为不超过1才行。

一直不对，结果发现最后才知道ab不能为零，mmp

    #include<stdio.h>  
    #include<string.h>  
    #include<math.h>  
      
    int main()  
    {  
        int a,b;  
        scanf("%d %d",&a,&b);  
        if(abs(b-a)<=1&&(b!=0||a!=0))  
        {  
            printf("YES\n");  
        }  
        else  
        {  
            printf("NO\n");  
        }  
        return 0;  
    }