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>

int x,ans,i ;

int main(void){

    scanf ("%d",&x) ;
    ans = 1 ;
    
    for (i=2; i<x; i++){
        
        int j ;
        for (j=i*i; j<x; j=j*i){
            
            if (ans < j){
            ans = j ;
            }
        }
    }
    
    printf ("%d",ans) ;
    
    return 0 ;
}