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)

#include "stdio.h"
#include "math.h"

int main(){
	int a;
	scanf("%d", &a);
	int max=1;
	int i;
	for (i=2;i<=31;i++){
		if(i*i>a)break;
	
		int j=i*i;
	
		while(j*i<=a){
			j*=i;
		}
		if(max<j)max=j;
		
	}
	printf("%d",max);
	
return 0;

}