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 a;
  cin >> a;
  int max = 1;
  for(int i = 1;i<33;i++){
    for(int j = 2;j<10;j++){
      if(pow(i,j) <= a && max < pow(i,j))
        max = pow(i,j);
    }
  }
  cout << max << endl;
}
  