Dasha and Stairs
time limit per test 2 second memory limit per test 256 megabytes
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.

传送门:CF761A

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.

Sample Input

1
2 3

Sample Output

1
YES

题解

trick题,注意有a=0&b=0的错误特解
## AC code:(不包含输入类)
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import java.io.*;  
import java.util.*;
public class Main {

public static void main(String[] args) {
Scanner sc= new Scanner(System.in);
while(sc.hasNext()){
int a=sc.nextInt();
int b=sc.nextInt();
if(Math.abs(a-b)>=2||a==0&&b==0){
System.out.println("NO");
}
else
System.out.println("YES");
}

}

}