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,t,i,j,a=0;

	scanf("%d",&x);

	if(x==1){
		printf("1");
		return 0;
	}
	for(i=2;i<sqrt(x);i++){
		t=0;
		for(j=2;(t=pow(i,j))<x;j++)
			if(a<t)
				a=t;
	}
	printf("%d",a);
	return 0;
}