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 <iostream>
using namespace std;
int x, mx=1, a;
int main() {
	cin>>x;
	for(int i=2; i*i<=x; i++) {
		for(a=i*i; a<=x; a*=i) mx = max(mx, a);
	}
	cout<<mx;
	return 0;
}