#include <iostream>
using namespace std;
int main() {
    int a;
    cin >> a;
    if (a < 100 and a>9) {
        if (a % 2 == 0) {
            cout << a * 4;
        }
        else {
            cout << a * 2;
        }
    }
    else {
        cout << "0";
    }
    return 0;
}

a=int(input())
if a>9 and a<100:
    if a%2==0:
        c=a*4
    else:
        c=a*2
else:
    c=0
print(c)