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 (Clang 3.8.0) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <math.h>
int main(){
	double  x;
	int y[10],max;
	scanf("%lf", &x);
	int i;
	for (i = 0;i < 11;i++){
		y[i] = pow(x,1.0/(2.0+i));
		y[i] = pow(y[i],2+i);
	}
	
	max = y[0];
	int s;
	for (s = 1;s < 11;s++){
		if (max < y[s])
			max = y[s];
	}
	printf("%d", max);
}