#include<iostream>
#include<string>
#include<vector>
#include<numeric>
#include<math.h>
#include<algorithm>
#include<iomanip>
#include<bitset>
using namespace std;

int main() {

	int S, W;
	cin >> S >> W;

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

	return 0;
}
