#include<stdio.h>
#include<math.h>
#include<iostream>
#include<string>
#include<vector>
using namespace std;
int main() {
	int S;
	int W;
	cin >> S >> W;
	if (W - S >= 0) {
		cout << "unsafe" << endl;
	}
	else {
		cout << "safe" << endl;
	}
	}