import java.util.*;
public class Plo{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long visina = sc.nextInt();
		long sirina = sc.nextInt();
		long k = sc.nextInt();
		long stPloscic = (visina/(1 << k))*(sirina/(1 << k));
		for (long i = k - 1; i >= 0; i--) {
			if ((sirina & (1 << i)) > 0)
				stPloscic += (visina / (1 << i));
			if ((visina & (1 << i)) > 0)
				stPloscic += (sirina / (1 << i));
			if ((sirina & (1 << i)) > 0 && (visina & (1 << i)) > 0)
				stPloscic--;
		}
		System.out.println(stPloscic);
	}
}