#include "bits/stdc++.h"
#pragma GCC optimize "03"
using namespace std;
 
#define int long long int
#define ld long double
#define pi pair<int, int>
#define pb push_back
#define fi first
#define se second
#define IOS ios::sync_with_stdio(false); cin.tie(0); cout.tie(0)
#ifndef LOCAL
#define endl '\n'
#endif
 
const int N = 2e5 + 5;
const int mod = 1e9 + 7;
const int inf = 1e9 + 9;

signed main() {
	IOS;
	int s, w;
	cin >> s >> w;
	if(w > s)
	cout << "unsafe";
	else
	cout << "safe";	
	return 0;
}