x = int(input())
y = int(input())
l = int(input())
order_counter = 0
move_counter = 0
rotation_counter = 0

if y >= 0:
    if y != 0:
        q, mod = divmod(abs(y),l)
        if mod == 0:
            move_counter += q
        else:
            move_counter += q + 1
            
    if x != 0:
        rotaition_counter += 1
        q, mod = divmod(abs(x), l)
        if mod == 0:
            move_counter += q
        else:
            move_counter += q + 1
else:
    rotaition_counter += 2
    q, mod = divmod(abs(y),l)
    if mod == 0:
        move_counter += q
    else:
        move_counter += q + 1
    q, mod = divmod(abs(x), l)
    if mod == 0:
        move_counter += q
    else:
        move_counter += q + 1
order_counter = rotaition_counter + move_counter        
 
print(order_counter)