#include <iostream>
#include <string>
#include <cstring>
#include <algorithm>
#include <functional>
#include <cmath>
#include <set>
#include <queue>
#include <deque>
#include <vector>
#include <climits>
#include <sstream>
#include <iomanip>
#include <map>
#include <stack>
using namespace std;
typedef unsigned long long ull;
typedef long long ll;

int main()
{
	int S, W;
	cin >> S >> W;

	if (W >= S)
	{
		cout << "unsafe" << endl;
	}
	else
	{
		cout << "safe" << endl;
	}

	return 0;
}