import java.util.Arrays;
import java.util.Comparator;
import java.util.PriorityQueue;
import java.util.Scanner;

class Main {

	public static void main(String[] args) {
		new Main().run();
	}
	
	double pow(double a,long n) {
		double ret=1;
		for(;n>0;n/=2,a*=a)if(n%2==1)ret*=a;
		return ret;
	}

	void run() {
		Scanner sc = new Scanner(System.in);
		int n=sc.nextInt();
		int m=sc.nextInt();
		double p=sc.nextDouble();
		long center=Math.max(n-2, 0)*Math.max(m-2, 0);
		long lateral_side=Math.max(m-2,0)*Math.min(n,2);
		long vertical_side=Math.max(n-2, 0)*Math.min(m,2);
		long corner=Math.min(2, n)*Math.min(2, m);
		long area_center=5;
		long area_corner=1+Math.min(n-1,1)+Math.min(m-1,1);
		long area_lateral_side=3+Math.min(n-1, 1);
		long area_vertical_side=3+Math.min(m-1, 1);
		System.out.println(center*pow(p,area_center)+corner*pow(p,area_corner)+lateral_side*pow(p,area_lateral_side)+vertical_side*pow(p,area_vertical_side));
	}

	void tr(Object... objects) {
		System.out.println(Arrays.deepToString(objects));
	}
}