#include <cassert>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <set>
using namespace std;
double n,X,Y;
int main() {
	// c++20 test
	set<int> s = {1, 2};
	assert(s.contains(2));
	assert(string("ans").starts_with("a"));

	cin >> n;
	while (n--) cin >> X, Y += X * X * X;
	cout << setprecision(20) << cbrt(Y) << endl;
}