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 9.2.1) (judge verdict: Wrong Answer)

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

int main(void)
{
  int x;
  scanf("%d",&x);

  int i,j,ans=1;
  for(i=1;i<x;i++)
    for(j=2;j<11;j++){
      if((pow(i,j)<=x)&&(pow(i,j)>ans))
        ans = pow(i,j);
      else if(pow(i,j)>x)
        break;
      printf("pow(%d,%d) = %.0lf\n",i,j,pow(i,j));
    }

  printf("%d\n",ans);
  return 0;
}