text: #include <iostream>
  #include <vector>
  #include <algorithm>
  #include <string>
  #include <cmath>
  #include <cctype>
  
  using namespace std;
  
  int main(){
      int s;
      int w;
      cin >> s >> w;
      if(w >= s){
          cout << "unsafe" << endl;
      }
      else{
          cout << "safe" << endl;
      }
  }