#include <iostream>
#include <string>
#include <cstring>
#include <vector>
#include <numeric>
#include <cstdlib>
#include <map>
#include <set>
#include <algorithm>
#include <math.h>
 
using namespace std;

int main() {
    int S,W;

    cin >> S >> W;

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

    return 0;
}
