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 "bits/stdc++.h"
using namespace std;

int main(void) {
	int x;
	cin >> x;

	int ans = -1, bp;

	for(int b=1;b<=32;b++) {
		for(int p=2;p<=10;p++) {
			bp = pow(b,p);
			if(bp <= x) ans = max(ans, bp);
		}
	}

	cout << ans << endl;

}
