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(void){

  int X; cin >> X;
  int max = 1;
  for(int i = 2 ; i < X / 2 ; i++){
    int a = i;
    while(a <= X)  a *=i;
    a /= i;
    max = (max < a)? a : max;
  }

  printf("%d\n", max);

return 0;
}