#include<bits/stdc++.h>
using namespace std;

#define dbg(a)  cerr << __LINE__ << ": " << #a << " = " << a << '\n'

typedef long long ll;

int main(){
  int a, b; cin >> a >> b;
  if(a<=b) cout << "unsafe" << endl;
  else cout << "safe" << endl;
  return 0;
}