#include<bits/stdc++.h>
#define ff first
#define ss second
#define len(x) (int)(x.size())
#define all(x) x.begin(), x.end()
using namespace std;
using ll = long long;
using ii = pair<int, int>;

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