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)

/*
 * main.c
 *
 *  Created on: 2019/03/06
 *      Author: family
 */


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

int main()
{
    int x;
    int i = 0;
    int j= 0;
    int ans = 0;
    int temp = 0;
    scanf("%d", &x);

    for(i = 1; i <= 31; i++) {
    	for( j = 2; j <= 10; j++) {
    		temp = pow(i,j);
    		if ((temp <= x) && (temp >= ans)) {
    			ans = temp;
    		}
    	}
    }
    printf("%d",ans);
	return 0;
}