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 main()
{
	int n,max,i,j,k;
	cin>>n;
	max=0;
	if(n<=3){cout<<"1";return 0;}
	for(i=2;i*i<=n;i++){
		j=2;
		while(pow(i,j)<=n)j++;
		j-=1;
		if(pow(i,j)>=max)max=pow(i,j);
	}
	cout<<max;
}