Problem:
Score : 200 points

Problem Statement

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.

Sample Input 1

10

Sample Output 1

9

There are four perfect powers that are at most 10: 1, 4, 8 and 9.
We should print the largest among them, 9.

Sample Input 2

1

Sample Output 2

1

Sample Input 3

999

Sample Output 3

961

Solution in C (GCC 5.4.1) (judge verdict: Accepted)

#include<stdio.h>
#include<math.h>

int main()
{
  int x;
  
  scanf("%d",&x);
  
  int ans=1;
  int i,j;
  
  for(i=1;i<=x;i++)
  {
    for(j=2;j<=10;j++)
    {
      if(x>=pow(i,j)&&ans<=pow(i,j))
      {
        ans=pow(i,j);
      }
    }
  }
  
  printf("%d\n",ans);
  
  return 0;
}