#ロボットの操縦

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

count = abs(X) // L + min(abs(X) % L , 1)
count += abs(Y) // L + min(abs(Y) % L , 1)

if Y >= 0 and X != 0:
    count += 1
elif Y < 0:
    count += 2

print(count)