#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#ifdef TEST
#define getchar_unlocked _getchar_nolock
#endif
#define int long long
#define ins insert
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define pf push_front
#define pp pop
#define ppb pop_back
#define ppf pop_front
#define eb emplace_back
#define g0(a) get<0>(a)
#define g1(a) get<1>(a)
#define g2(a) get<2>(a)
#define g3(a) get<3>(a)
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
typedef long double ld;
typedef long long ll;
typedef tree<pair<int, int>, null_type, less<pair<int, int> >, rb_tree_tag, tree_order_statistics_node_update> ordered_set;

main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	int s, w;
	cin >> s >> w;
	if (w >= s) cout << "unsafe\n";
	else cout << "safe\n";
}
