#include<bits/stdc++.h>
#define ll long long
#define M 1000000007

using namespace std;

// Solve function here


// End Solve function

int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
    //ifstream cin("input.in");
	//clock_t start, finish;
	int n, m; cin >> n >> m;
	if(m >= n) cout << "unsafe\n";
	else cout << "safe\n";
	return 0;
}
