table

#include <iostream>
using namespace std;

int main()
{
    unsigned long a, b, k;
    cin >> a >> b >> k;
    if (a<k || b<k)
        cout << 0;
    else if (a>=b && b/k==1)
        cout << a/k;
    else if (a<=b && a/k==1)
        cout << b/k;
    else if (a>b && b/k>=2)
        cout << 2*(a/k) + 2*((b/k)-2);
    else
        cout << 2*(b/k) + 2*((a/k)-2);

    return 0;
}