x = int(input())
y = int(input())
l = int(input())

count = 0
if x != 0 and y >= 0:
    count += 1
if y < 0:
    count += 2
x = abs(x)
y = abs(y)
count += x // l
count += 1 if x % l > 0 else 0
count += y // l
count += 1 if y % l > 0 else 0
print(count)