#include <iostream>
#include <string>
#include <vector>
#include <stdio.h>
#include <cmath>
#include <algorithm>
#define _USE_MATH_DEFINES
#include <math.h> //円周率はM_PI
using namespace std;


int main() {
	int s, w;
	cin >> s >> w;

	if (w >= s) {
		cout << "unsafe" << endl;
	}
	else {
		cout << "safe" << endl;
	}

}
