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