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(){
  int X;
  int ans=1,p;
  cin >> X;
  for(int i=2;i<=40;i++){
    p=i;
    if(p*p>X) break;
    while((p*i)<=X){
      p*=i;
    }
   if(X!=1) ans=max(ans,p);
  }

  cout << ans <<endl;
  return 0;
}
