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;

//const int MAX_N = 100;

int main(){
	int x,ans=1,num;
	cin>>x;

	for (int i = 2; i <= x; i++){
		num=i*i;
		while(num<=x){
			ans=max(ans, num);
			num*=i;
		}
	}
	cout<<ans<<endl;
}
