#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <math.h>
#include <algorithm>
#include <string>
#include <string.h>
#include <vector>
#include <functional>
#include <queue>
#include <unordered_set>

using namespace std;
typedef long long ll;

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