#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<utility>
#include <functional>
#include <set>
#include <map>
#include <queue>
#include <cmath>
#include <stack>

using namespace std;

int main() {
	int n, k;
	cin >> n >> k;
	if (k >= n)cout << "unsafe";
	else cout<<"safe";
}