#include <bits/stdc++.h>
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
using namespace std;
constexpr long long int mod = 1000000007;


//M*X+R=Y

int main() {
	int A, B;
	cin >> A >> B;
	if (A > B)cout << "safe";
	else cout << "unsafe";
}