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;
cin >> x;
int ans = 1;
for(int i = 2;i < x;i++){
int hoge = i*i;
  while(hoge <= x){
    ans = max(ans,hoge);

    hoge *= i;


  }
} 
cout<< ans <<endl;
}