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<cstdio>
using namespace std;
int x,mx=1;
int main()
{
	scanf("%d",&x);
	for(int i=2,tmp;i*i<=x;i++)
	{
		for(int tmp=i*i;tmp<=x;tmp*=i)
		{
			if(tmp>mx)mx=tmp;
		}
	}
	printf("%d",mx);
}