You are given a positive integer X. Find the largest perfect power that is at most X. Here, a perfect power is an integer that can be represented as b^p, where b is an integer not less than 1 and p is an integer not less than 2.

Constraints

* 1 ≤ X ≤ 1000
* X is an integer.

Input

Input is given from Standard Input in the following format:


X


Output

Print the largest perfect power that is at most X.

Examples

Input

10


Output

9


Input

1


Output

1


Input

999


Output

961
#include"bits/stdc++.h"

using namespace std;

int main() {
	int X;
	cin >> X;
	int ans = 1;

	for (int i = 2; i < 40; i++) {
		int num = i*i;
		while (num <= X) {
			ans = max(ans, num);
			num *= i;
		}
	}

	cout << ans << endl;

	return 0;
}