#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
using namespace std;

int main() {

    int S,W;
    cin >> S >> W;
    
    if (W >= S) {
        cout << "unsafe" << endl;
    }
    
    else { cout << "safe" << endl;
         }
}

