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 makeList(int x)
{
	int ans=1;
	for(int i=2;i<=sqrt(x);i++)
	{
		int j=i;
		while((j*=i)<=x)
		  ans=max(ans,j); 
	}
	return ans;
} 

int main()
{
	int a;
	cin>>a;
	cout<<makeList(a)<<endl;
	return 0;
} 