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 <stdlib.h>
#include <math.h>

int main(void){
    
    int a, tei, j, max = 0;
    scanf("%d", &a);
    
    for (tei = 2; tei*tei<=a; tei++) {
        for (j = 2; (int)pow(tei, j)<=a; j++) {
            max = (int)pow(tei, j) > max ? (int)pow(tei, j) : max;
        }
    }
    
    printf("%d\n", max);
    
    return 0;
}