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
// B - Exponential
#include <bits/stdc++.h>
using namespace std;

int main(){
	int x; cin>>x;
	int ans = 1;
	for(int i=2; i*i<=x; ++i)
		for(int a=i*i; a<=x; a*=i) ans = max(ans, a);
	cout<< ans <<endl;
}
