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;
long long a,b;
int main()
{
	cin>>a;
	for(int s=1;s<=32;s++)
	{
		for(int v=2;v<=10;v++)
		{
			if(pow(s,v)<=a)b=max(b,(long long)pow(s,v));
		}
	}
	cout<<b<<endl;
}