#include <bits/stdc++.h>
 
using namespace std;

using LL = long long;
using LD = long double;
 
LL mod = 1e9+7;

int main()
{
	LL s, w;
	cin >> s >> w;

	if (w >= s) {
		cout << "unsafe\n";
	}
	else {
		cout << "safe\n";
	}
}

