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>
#include <algorithm>
using namespace std;
typedef long long ll;
int main(void){
  int x,a=2,l,s=1;
  cin >> x;
  while (a*a<=x){
    l=1;
    while (l*a<=x) l*=a;
    s=max(s,l);
    a++;
  }
  cout << s << endl;
  return 0;
}