#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==-1 && y==1) cout<<"yes"; else cout<<"no"; return 0; }