#include <iostream>
using namespace std;
#define vi vector<int>
// #define vs vector<string>
// #define mii map<int, int>

void show(auto a){
  int i = 0;
  while(i < a.size()){
    cout<<a[i]<<" ";
    i++;
  }
  cout<<endl;
}


int main(){
  ios_base::sync_with_stdio(false);
  int s, w;
  cin>>s>>w;
  if(w>=s) cout<<"unsafe"<<endl;
  else cout<<"safe"<<endl; 

}