#include <bits/stdc++.h>

using namespace std;

int main() {
    //cin读入优化
    std::ios::sync_with_stdio(false);
    int x, y;
    cin >> x >> y;
    if (x >= -1 && x <= 1 && y >= -1 && y <= 1) {
        cout << "yes";
    } else {
        cout << "no";
    }
    return 0;
}