#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
const double PI = 4*atan(1);
const int INF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3f;
const double EPS = 1e-9;
const string YES = "Possible";
const string NO = "Impossible";
#define pb push_back
#define mp make_pair

int S, W;

void solve()
{
	if(W >= S) cout << "unsafe\n";
	else cout << "safe\n";
}

int main()
{
	ios::sync_with_stdio(false);
	cin >> S >> W;
	solve();
	return 0;
}