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 main() {
	int list[] = {4, 8, 9, 16, 25, 27, 32, 
		36, 49, 64, 81, 100, 121, 125, 128, 
		144, 169, 196, 216, 225, 243, 256, 
		289, 324, 343, 361, 400, 441, 484, 
		512, 529, 576, 625, 676, 729, 784, 
		841, 900, 961, 1000};

	int x, val, i;
	val = scanf("%d", &x);
	if (val == 0) return 1;

	for (i = 0; i < 40; i++) {
		if (list[i] <= x) val = i;
		else break;
	}

	printf("%d", list[val]);
}