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=0;
  	cin>>n;
  	
  	for(int i=1;i<34;i++){
      for(int j=2;j<11;j++){
		if(pow(i,j)<=n && pow(i,j)>max){
			max=pow(i,j);
        }
      }
    }
	 	
    cout<<max<<endl;
}