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 n,m;

int main(){
  int i,j;
  double max=0;
  cin >> n;
  for(i=1;i<=1000;i++)for(j=2;j<10;j++)if(pow(i,j)<=(double)n&&pow(i,j)>max){
	max=pow(i,j);
      }
  cout << (int)max << endl;

  return 0;
}
