#include <iostream>
#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
#include <vector>
#include <numeric>
#include <map>
#include <cmath>
#include <iomanip>
#include <queue>
using ll =long long;
using vi = vector<int>;
using vl = vector<ll>;
using vvi = vector<vi>;
using vs = vector<string>;

int main() {
    int S, W;
    cin >> S >> W;

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

}
