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>
#include <math.h>
using namespace std;
int main(void){
    int x,i,j,max = 1;
	cin >> x;
	for(i = 2; i <= x/2; i++){
		for(j = 1; pow(i,j) <= x; j++){}
		if(pow(i,j-1) > max)
			max = pow(i,j-1);
	}
	cout << max <<endl;
}
