#include <bits/stdc++.h>
using namespace std;
int main()
{
    int a,b;
    cin>>a>>b;
    if(abs(a)<=1&&abs(b)<=1)cout<<"yes";
    else cout<<"no";
    return 0;
}

#include<iostream>
#include<cstdio>
#include<cmath>
#include<algorithm>
using namespace std;
int main(){
	double x,y;
	cin >> x >> y;
	bool bl1=x >= -1;
	bool bl2=1 >= x;
	bool bl3=y >= -1;
	bool bl4=1 >= y;
	if(bl1 == 1 && bl2 == 1){
		if(bl3 == 1 && bl4 == 1){
			cout << "yes";
		}else{
			cout << "no";
		}
	}else{
		cout << "no";
	}
	return 0;
}