import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		long m = sc.nextLong();
		double p = sc.nextDouble();
		sc.close();

		if (m < n) {
			long t = m;
			m = n;
			n = t;
		}
		if (n == 1) {
			if (m == 1) {
				System.out.println(p);
			} else {
				double p2 = p * p;
				double p3 = p2 * p;
				System.out.println(2 * p2 + (m - 2) * p3);
			}
		} else {
			double p3 = p * p * p;
			double p4 = p3 * p;
			double p5 = p4 * p;
			System.out.println(4 * p3 + (n * 2 + m * 2 - 8) * p4 + (n - 2) * (m - 2) * p5);
		}
	}
}