#include <bits/stdc++.h>
#include <math.h>
using namespace std;
typedef long long ll;
  
int main(void){
    int s, w;
    
    cin >> s >> w;
    //cout << sqrt(a) << " " << sqrt(b) << " " << sqrt(c) << endl;
    if (s<=w) {
        cout << "unsafe";
    } else {
        cout << "safe";
    }
    return 0;
}