import math 
x = int(input())
y = int(input())
moving = int(input())
count = 0
# where quadrant? 
if x == 0:
    count = 0
elif y >= 0:
    count = count + 1
else:
    count = count + 2
x, y = abs(x), abs(y)
while x > 0:
    sep_x = math.floor(x / moving)
    count = count + sep_x
    x = x - sep_x * moving
while y > 0:
    sep_y = math.floor(y / moving)
    count = count + sep_y
    y = y - sep_y * moving
print(count)