#include <stdio.h>
#include <iostream>
#include <vector>
#include <string>
#include <cstdint>
#include <algorithm>
#include <utility>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
int main(){
int S, W; cin >> S >> W;
if(S > W){
  cout << "safe" << endl;
}
else{
  cout << "unsafe" << endl;
}
}