#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cstdlib>
using namespace std;
void YES(){cout << "YES" << endl;}
void NO(){cout << "NO" << endl;}
void Yes(){cout << "Yes" << endl;}
void No(){cout << "No" << endl;}
int main() {
  int N,X;
  cin >> N >> X;
  if(N>X){
    cout << "safe";
  }
  else{
    cout << "unsafe";
  }
  cout << endl;
  return 0;
}
