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

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