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(){
    int i,j=0,n,val,a[100],count=0,max;
    
    scanf("%d",&n);
    
    for(i=1;i<=n;i++){
        val=sqrt(i);
       // printf("%d ",val);
        if(i==val*val){
            a[j]=i;
            count++;
            j++;
        }
    }
    
    max=a[0];
    
    for(j=0;j<count;j++){
        //printf("%d ",a[j]);
        if(a[j]>max){
            max=a[j];
        }
    }
    
    printf("%d\n",max);
    
    return 0;
}