time limit per test2 seconds

memory limit per test256 megabytes

inputstandard input

outputstandard output

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

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.

【题目链接】:http://codeforces.com/contest/761/problem/A

【题解】



一段区间里面,偶数和奇数的个数的差的绝对值不会超过1;

但是有个Hack点0 0;

一段区间里面不可能既没有奇数也没有偶数;



【完整代码】

#include <bits/stdc++.h>

using namespace std;

int a,b;

int main()

{

    cin >> a >> b;

    int temp = abs(a-b);

    if (temp<=1)

    {

        if (a==0 && b==0)

            puts("NO");

        else

            puts("YES");

    }

    else

        puts("NO");

    return 0;

}