using namespace std;

int main() {
	long long a, b;
	cin >> a >> b;
	if (a > 1 || a < -1 || b > 1 || b < -1) {
		cout << "no";
	} else
		cout << "yes";
	return 0;
}

#include <bits/stdc++.h> using namespace std;

int main() { long long a, b; cin >> a >> b; if (a > 1 || a < -1 || b > 1 || b < -1) { cout << "no"; } else cout << "yes"; return 0; }

#include<bits/stdc++.h> using namespace std; int main(){ long long a,b; cin>>a>>b; if(a>1||a<-1||b>1||b<-1){ cout<<"no"; return 0; } cout<<"yes"; return 0; }