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,ans=1;
  cin>>x;
  for(int i=2;i<=x;i++){
    int t=i*i;
    while(t*i<=x){
      t*=i;
      //cout<<t<<endl;
    }
    if(t<=x)ans=max(ans,t);
  }
  cout<<ans<<endl;
  return(0);
}