def main():
    x = int(input())
    y = int(input())
    max_length = int(input())
    if y < 0:
        operation = 2
    elif x != 0:
        operation = 1
    else:
        operation = 0
    x = abs(x)
    y = abs(y)
    operation += x // max_length + (0 if x % max_length == 0 else 1)
    operation += y // max_length + (0 if y % max_length == 0 else 1)
    print(operation)


if __name__ == '__main__':
    main()