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<iostream>
using namespace std;
int main(){
	int n;
  	cin >> n;
  	int ans = 1;
  	for(int i = 2; i<n; i++){
		int t = i*i;
    	while(t<=n){
			if(ans<t)ans = t;
			t*=i;
  		}
    }
  	cout << ans << endl;
}
