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 b=2; b<=x; b++){
    int tmp=b*b;
    while(tmp<=x){
      ans=max(ans,tmp);
      tmp*=b;
    }
  }
  cout<<ans;
}