#include <bits/stdc++.h>
using namespace std;
int main()
{
    int n, m, p = 0;
    cin >> n >> m;
    if (n == 1)
    {
        cout << n / m << endl;
    }
    else
    {
        n = n / 2;
        for (int i = 1; i <= n; i++)
        {
            if ((m * i) == n)
            {
                p = i;
            }
        }
 
        cout << p * 2 << endl;
    }
}