#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
using ll = long long;

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