#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#define rep(i, a, b) for(int i = (a); i < (b); i++)
#define ill long long
using namespace std;

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