#ロボットの操縦

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

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

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

print(count)