#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(w >= s){
        cout << "unsafe" << endl;
    }
    else{
        cout << "safe" << endl;
    }


    return 0;
}