#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp> 
#include <ext/pb_ds/tree_policy.hpp> 
using namespace __gnu_pbds; 
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update> 
#pragma GCC target ("avx2")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
#define fi first
#define se second
#define endl '\n'
#define int int64_t
#define double long double
// mt19937 rnd(time(0));
// const double TIME_LIMIT = 1.8;
// Heuristic TL: clock() < TIME_LIMIT * CLOCKS_PER_SEC
const int MAXN = 1000001;
const int INF = numeric_limits<int>::max() >> 3;
const int MOD = (int)998244353;

signed main(){
	ios_base::sync_with_stdio(0); 
	cin.tie(0); 
	cout.tie(0); 
	// freopen("FDT.txt","r",stdin);
	int s, w;
	cin >> s >> w;
	cout << (w >= s ? "unsafe": "safe");
}