x_target = int(input())
y_target = int(input())
speed = int(input())

count = 0

if x_target != 0:
    count += 1
    if y_target < 0:
        count += 1
elif y_target < 0:
    count += 2

if x_target % speed != 0:
    count += 1
count += (abs(x_target) // speed)


if y_target % speed != 0:
    count += 1
count += (abs(y_target) // speed)

print(count)