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

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