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 x;
	cin>>x;
	int ans=0;
	for(int i=1;i<=40;++i){
		for(int j=2;j<=10;++j){
			if(pow(i,j)<=x)
				ans=max(ans,int(pow(i,j)));
		}
	}
	cout<<ans;
}