#define _USE_MATH_DEFINES
#include <iostream>
#include <string>
#include <math.h>
#include <vector>

using namespace std;

int main() {

	int S, W;

	cin >> S;
	cin >> W;

	if (W < S) {
		cout << "safe";
	}
	else {
		cout << "unsafe";
	}

	return 0;

}