#include<bits/stdc++.h> using namespace std; int main(){ int x,y; 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; }