#include <iostream>
#include <vector>
#include <map>

using std::cout;
using std::endl;
using std::cin;

int main(int argc, char* argv[])
{
  int s,w;
  cin >> s >> w;
  std::string result =  (w >= s) ? "unsafe" : "safe";
  std::cout << result << std::endl;
  return 0;
}
