import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int h = sc.nextInt();
        int w = sc.nextInt();
        double rate = sc.nextDouble();
        if (h == 1 && w == 1) {
            System.out.println(rate);
        } else if (h == 1) {
            double ans = Math.pow(rate, 2) * 2 + Math.pow(rate, 3) * (w - 2);
            System.out.println(ans);
        } else if (w == 1) {
            double ans = Math.pow(rate, 2) * 2 + Math.pow(rate, 3) * (h - 2);
            System.out.println(ans);
        } else {
            double ans = Math.pow(rate, 3) * 4;
            ans += Math.pow(rate, 4) * (w - 2) * 2;
            ans += Math.pow(rate, 4) * (h - 2) * 2;
            ans += Math.pow(rate, 5) * (w - 2) * (h - 2);
            System.out.println(ans);
        }
    }
}