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<algorithm>
using namespace std;
int n,ans;
int main()
{
	scanf("%d",&n);if (n<4) {printf("1\n");return 0;}
	for (int i=2;i<n;++i)
	for (int s=i;;){
		s*=i;if (s>n) break;
		if (s>ans) ans=s;
	}
	printf("%d\n",ans);
	return 0;
}