#include <bits/stdc++.h>
using namespace std;
const int MOD = (int)1e9 + 7;
const int INF = 100100100;
const double PI = 3.14159265358979323846;
typedef long long ll;
#define FOR(i, a, b) for (ll i = (a); i < (b); ++i)
#define REP(i, n) for (ll i = 0; i < (n); ++i)

int main() {
  ll s, w;
  cin >> s >> w;
  if (s > w) {
    cout << "safe" << endl;
  } else {
    cout << "unsafe" << endl;
  }
  return 0;
}