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<stdio.h>
#include<stdlib.h>
#include<math.h>
int main()
{
  int a,b,c,q,x;
  a=0;
  scanf("%d",&x);
  for(b=1;b<33;b++)
  {
   for(q=2;q<11;q++)
    {
     c=pow(b,q);
     if(c<=x){
       a=fmax(a,c);
     }
   }
 }
  printf("%d",a);
  return 0;
}