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 i,n,m,ans;
  scanf("%d",&n);
  ans=1;
  for(i=2;i<=n;i++){
    m=2;
    while(n>=pow(i,m)){
      if(ans<pow(i,m)){ans=pow(i,m);}
      m++;
    }
    if(m==2){break;}
  }
  printf("%d",ans); 
  return 0;
}