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>
#include<cmath>
using namespace std;
int main()
{
  int x,i,j,t,res=1;
  cin >> x;
  t=(int)sqrt(x);
  for(i=t;i>1;i--){
    j=i;
    while(j*i<=x) j*=i;
    res=max(res,j);
  }
  cout << res << endl;
  return 0;
}