x = int(input())
y = int(input())
moving = int(input())
count = 0
# where quadrant? 
if y >= 0:
    count = count + 1
else:
    count = count + 2
x, y = abs(x), abs(y)
while x > 0:
    count = count + 1
    x_move = 1
    x = x - moving
while y > 0:
    count = count + 1
    y_move = 1
    y = y - moving
print(count)