666

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