import java.util.Scanner;

public class Run {
    public static void main (String arg[]) {
        Scanner scan = new Scanner(System.in);
        int X = scan.nextInt();
        int Y = scan.nextInt();
        int L = scan.nextInt();
        if (X < -1000000000||X > 1000000000||
            Y < -1000000000||Y > 1000000000||
            L < 1 || L > 1000000000) System.exit(1);

        int i = 0;
        if (Y >= 0) {
            i += Y/L;
            if (Y%L != 0) i++;
            if (X!=0) {
                X = Math.abs(X);
                i++;
                i += X/L;
                if (X%L != 0) i++;
            }
        } else {
            Y = Math.abs(Y);
            i += 2;
            if (X!=0) {
                X = Math.abs(X);
                i += X/L;
                if (X%L != 0) i++;
            }
            i += Y/L;
            if (Y%L != 0) i++;
        }

        System.out.println(i);
    }
}