#include<iostream>
#include<cmath>
using namespace std;
int main()
{
int x,y;
cin>>x>>y;
if(abs(x)<=1&&abs(y)<=1)
cout<<"yes";
else
cout<<"no";
}

#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
int main()
{
    int a,b;
    cin>>a>>b;
    if(abs(a)<=1&&abs(b)<=1)
        cout<<"yes";
    else
        cout<<"no";
}