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.

Examples

Input

10


Output

9


Input

1


Output

1


Input

999


Output

961
#include <cstdio>
#include <cmath>
#include <algorithm>
using namespace std;
int x,maxn=1;
int main()
{
	scanf("%d",&x);
	int c=sqrt(x);
	for(int b=2;b<=c;b++)
		for(int t=b*b;t<=x;t*=b)
			maxn=max(maxn,t);
	printf("%d",maxn);
	return 0;
}