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;
int main()
{
	cin>>X;
	int ans=1;
	for(int i=2;i<=X;i++)
	{
		int t=i*i;
		while(t<=X)
		{
			if(ans<t)ans=t;
			t*=i;
		}
	}
	cout<<ans<<endl;
}
