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

#define pb push_back
#define fi first
#define se second
typedef long long ll;

int main()
{
	ios_base::sync_with_stdio(false); cin.tie(NULL);

	int s, w;
	cin >> s >> w;
	if (s <= w)
		cout << "un";
	cout << "safe\n";
}
