#include <bits/stdc++.h>
#define rep(i,n) for (int i = 1;i <= (n); ++i)
using namespace std;
using ll = long long;
using P = pair<int,int>;

int main(){
    int s;
    int w;
    cin >> s >> w;

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

    return 0;
}

