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;cin>>X;
  int b=2,m=1;
  for(;b<=X;b++){
    int c=b*b;
    while(true){
      if(c<=X)m=max(m,c);
      else break;
      c*=b;
    }
  }
  cout<<m<<endl;
}