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 x = 1;
	for (int b = 1;b <= 31;++b) {
		for (int p = 2;p <= 9;++p) {
			if (x < pow(b, p) && pow(b, p) <= X) {
				x = pow(b,p);
			}
		}
	}
	cout << x << endl;
	return 0;
}