#include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<cmath>
#include <limits>
#include <iomanip>

using namespace std;


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