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<cmath>

using namespace std;

int main(){
  int n;
  cin >> n; 
 
  int res=1;
 for(int i=2;i*i<=n;i++){
   int exp=i*i;
   while(exp<=n){
    exp*=i;
   }
   res=max(res,exp/i);
 }
  
  cout << res << endl;
  
}