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 <stdio.h>
#include<math.h>
int i;
int j;
int k=2;
int a;
int max=1;
int main(){
scanf("%d",&i);
for(j=2;j<i;j++){
k=2;
while(1){
a=pow(j,k);
if(a>i)break;
if(max<a)max=a;
k++;
}
}
printf("%d",max);
}
