#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;

#define fi first
#define se second
#define mp make_pair
#define fastIO ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

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