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: Wrong Answer)

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

int main(void)
{
  int a,b,p,r,X;
  scanf("%d",&X);
	
 	for(X=X;X>0;X--)
    {
    	for(b=32;b>0;b--)
   	 	{
    	  r=X%b;
    	  if(r==0)
    	  {
    		for(p=10;p>1;p--)
            { 
              a=pow(b,p);
              if(a==X)      
                printf("%d\n",a);    
       	   }
          }    
          if(a==X)
      	 		 break;          
 	 	  }
      if(a==X)
      	 		 break;
    }
}