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

int main(){
  int S, W;
  cin >> S >> W;
  if(W >= S) cout << "un";
  cout << "safe" << endl;
}
