#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define mp make_pair
#define f first
#define s second
#define sz size()
#define ll long long
#define all(_v) _v.begin(), _v.end()

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