#include <iostream>
#include <algorithm>
#include <math.h>
#include <string.h>
#include <cstdio>
#include <utility>
#include <vector>
#include <map>
using namespace std;
typedef long long int ll;
typedef double db;
const int INF = 1e9 + 5;

void solve()
{
	int s, w;
	cin >> s >> w;
	if (s > w)
		cout << "safe" << endl;
	else
		cout << "unsafe" << endl;
}
int main()
{
//	int t;
//	cin >> t;
//	while (t-- > 0)
	solve();
}
