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 x,v,ans=1;cin>>x;
  for(int i=2;i<=sqrt(x);i++){
    v=i;
    while(v<=x){
      ans = max(v,ans);
      v*=i;
    }
  }
  cout<<ans<<endl;
}
