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()
{
    float a,i;
    int n,k=2,lrg,la=1;
    scanf("%d",&n);
    
    a=sqrt(n+1);
  
    for(i=2;i<=a;i++)
    {
        for(k=2;;k++)
        {
        if(pow(i,k)<n){
        lrg=pow(i,k);
                if(lrg>=la)
                la=lrg;
               }
        else
            break;
         }
    }
 
    printf("%d",la);
}