#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i = 0; i < (n); ++i)
using ll = long long;
int main() {
  int S,W;
  cin >> S >> W;
  
  if(W >= S){
    cout << "unsafe" <<endl;
  }
  else{
    cout << "safe" <<endl;
  }
  
    
  
    return 0;
}