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

#include<bits/stdc++.h>
using namespace std;

int main(){
    int x,y;
    cin>>x>>y;
    if (y>=-1 && y<=1 && x>=-1 && x<=1)cout<<"yes";
    else cout<<"no";
	return 0;
}