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>
typedef long long ll;
using namespace std;
 
int main() {
	ll x,ma=-1,w;
	cin>>x;
	for(ll i=1;i<50;i++){
		for(ll j=2;j<50;j++){
			w=pow(i,j);
			if(w<=x){
				ma=max(ma,w);
			}
		}
	}
	cout<<ma<<endl;
	return 0;
}