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(void)
{
  int x;
  scanf("%d",&x);
  if(x==1){
    puts("1");
    return 0;
  }
  int max=0;
  for(double i=1;i<=x;i++){
    for(double j=2;j<=x;j++){
      // printf("%lf\n",pow(i,j));
      if(pow(i,j)>max&&pow(i,j)<=x){
        max=pow(i,j);
      }
    }
  }

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