#include <bits/stdc++.h>
using namespace std;
#define int long long
typedef pair<int,int> pi;
#define f first
#define s second
#define FAST ios_base::sync_with_stdio(0); cin.tie(0);
#define all(x) x.begin(),x.end()
typedef pair<int,pi> pp;
#define p(x,y,z) pp(z,pi(x,y))


int s,w;

int32_t main() {
	cin >> s >> w;
	if (w >= s) {
		cout << "unsafe";
	} else cout << "safe";
}


