#include <iostream>
#include <bits/stdc++.h>
#include <string>
#include <math.h>
#include <vector>
#include <algorithm>
#include <set>
using namespace std;

int main(){
  int s,w; cin>>s>>w;
  if(w>=s) cout<<"unsafe"<<endl;
  else cout<<"safe"<<endl;
  return 0;
}