#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
#include <string>
#include <vector>
#include <queue>
#include <map>
using namespace std;
typedef long long LL;

LL a,b;

int main(){
	ios::sync_with_stdio(false);
	cin >> a >> b;
	cout << (a <= b ? "unsafe" : "safe") << '\n';
	return 0;
}