#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const double EPS = 1e-9;
typedef vector<int> vint;
typedef pair<int, int> pint;
#define rep(i, n) REP(i, 0, n)
#define ALL(v) v.begin(), v.end()
#define MSG(a) cout << #a << " " << a << endl;
#define REP(i, x, n) for (int i = x; i < n; i++)
template <class T, class C> void chmax(T &a, C b) { a > b ?: a = b; }
template <class T, class C> void chmin(T &a, C b) { a < b ?: a = b; }

int main() {

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

  return 0;
}
