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 x, max = 1;

	scanf("%d", &x);
	int p;
	if (x != 1) {
		for (int i = 2; i <= x; ++i) {
			p = 2;
			while (pow(i, p) < x)
			{
				max = fmax(max, pow(i, p));
				++p;
			}
		}
	}
	else {
		max = 1;
	}

	printf("%d", max);

	return 0;
}