X = int(input())
Y = int(input())
L = int(input())

order = 0
shou, yo = divmod(abs(X), abs(L))

if X != 0:
    order = shou + 1  # 左右を向く分

if yo > 0:
    order += 1

shou, yo = divmod(abs(Y), abs(L))
order += shou

if yo > 0:
    order += 1

if Y < 0:
    order += 1

print(order)