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

count = 0

direction = 'N'

# change direction
if Y >= 0 and X < 0:
    count = 1
elif Y < 0 and X <= 0:
    count = 2
elif Y >= 0 and X > 0:
    count = 1
elif Y < 0 and X > 0:
    count = 2

# go
X = max([X, -1 * X])
Y = max([Y, -1 * Y])
count += int(X / L) if X % L == 0 else int(X / L) + 1
count += int(Y / L) if Y % L == 0 else int(Y / L) + 1

print(str(count))