#include <iostream>
#include <vector>
#include <utility>
#include <string>
#include <map>
#include <algorithm>

using namespace std;

int main() {
    int a, b;
    cin >> a >> b;
    if(b >= a){
        cout << "unsafe" << endl;
    } else {
        cout << "safe" << endl;
    }
  return 0;
}