#include <bits/stdc++.h>
using namespace std;
const double PI = 3.141593;
const long long MOD = (long long)1e9 + 7;
const long long INF = 100100100;
const double EPS = 1e-9;
template <class T>
bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
long long lcm(long long a, long long b) { return a * b / gcd(a, b); }
long long combination(long long n, long long r) {
  if (r * 2 > n) r = n - r;
  long long dividend = 1;
  long long divisor = 1;
  for (long long i = 1; i <= r; ++i) {
    dividend *= (n - i + 1);
    divisor *= i;
  }
  return dividend / divisor;
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long s, w;
  cin >> s >> w;
  if (s <= w) {
    cout << "unsafe" << endl;
  } else {
    cout << "safe" << endl;
  }
  return 0;
}
