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,a[1001]={0,1};
  for(int i=2;i<32;i++)
    for(int j=i*i;j<=1000;j*=i)
      a[j]=1;
  cin>>x;
  for(int i=x;i>=0;i--)
    if(a[i]==1){
      cout<<i<<endl;
      break;
    }
  return 0;
}