#include<bits/stdc++.h> 
using namespace std; 
long long x,y;
int main(){ 
	cin >> x >> y; 
	if(x >= -1 && x <= 1){ 
		if(y >= -1 && y <= 1){ 
			cout << "yes" << endl;
			exit(0);
		}else{ 
			cout << "no" << endl;
			exit(0); 
		} 
	}else{ 
		cout << "no" << endl; 
		exit(0); 
	}
	return 0; 
}