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

north = max(0, (y + l - 1) // l)
east_west = (abs(x) + l - 1) // l
south = max(0, (-y + l - 1) // l)

ans = north
if south > 0:
    ans += east_west + south + 2
elif east_west > 0:
    ans += east_west + 1

print(ans)