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;
const int xm=1e3;
bool b[xm+1];
int x;
int main(){
  b[1]=1;
  for(int i=2;i*i<=xm;i++){
    for(int j=i*i;j<=xm;j*=i){
      b[j]=1;
    }
  }
  cin>>x;
  while(!b[x])x--;
  cout<<x<<endl;
}
