#include <iostream>
#include <vector>
#include <queue>
#include <string>
#include <algorithm>
typedef long long ll;
const int MOD = 1000000007;
#define PI 3.141592653589
using namespace std;

int main() {
	int s, w;
	cin >> s >> w;
	cout << (s <= w ? "unsafe": "safe") << endl;
	return 0;
}
