#include <string>
#include <iostream>
#include <vector>
#include <string>
#include <utility>
#include <algorithm>
#include <math.h>
 
using namespace std;
int main() {
	cin.tie(0);
   	ios::sync_with_stdio(false);
 
	int x,y;
	cin >> x >> y;
    if(y>=x){
      cout << "unsafe" << "\n";
    }else{
      cout << "safe" << "\n";
    }
  
}