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<iostream>
#include<cmath>
#include<algorithm>
using namespace std;

int main() {
    int x,xmax=0;
    cin>>x;
    for(int i=2; i<=9; i++) {
        xmax = max(xmax, (int)pow((int)pow((float)x, (1/(float)i)), i));
    }
    cout<<xmax<<endl;
}