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;
using ll = long long;


int main()
{
    int n, ans = 1;
    cin >> n;
    for(int i = 2; i * i <= n; i++){
        for(int j = i * i; j <= n; j *= i)ans = (ans < j? j : ans);
    }
    cout << ans << endl;
}