#include <algorithm>
#include <bitset>
#include <climits>
#include <iostream>
#include <map>
#include <string>
#include <vector>

using namespace std;
using ll = long long int;

int main() {
  ll S, W;
  cin >> S >> W;

  if (W >= S) {
    printf("unsafe");
  } else {
    printf("safe");
  }
}