import java.util.Scanner;

public class ThreatreSquare1 { public static void main(String[] args) { Scanner sc = new Scanner(System.in); long n = sc.nextInt(); long m = sc.nextInt(); long a = sc.nextInt();

long count = 0;



    long x= m / a;
    if(m % a != 0){
        x += 1;
    }

    count = n / a;
    if(n%a != 0){
        count+=1;
    }



    System.out.println(count * x);


}

}