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>
using namespace std;
int main(){
  int x; cin >> x;
  int ans=1;
  for(int b=2;b<=x;b++){
    int num = b*b;
    while(num<=x){
      if(ans<=num) ans = num;
      num *= b;
    }
  }
  cout << ans << endl;
  return 0;
}