#include <math.h>

#include <algorithm>
#include <cstring>
#include <iostream>
#include <string>
#include <vector>
using namespace std;
#define rep(i, n) for (int i = 0; i < n; i++)
using ll = long long;

int main() {
  int s, w;
  cin >> s >> w;

  if (s <= w)
    cout << "unsafe";
  else
    cout << "safe";
  return 0;
}
