x = int(input())
y = int(input())
l = int(input())
ans = 0
if y == 0:
    if x == 0:
        print(0)
        exit()
    ans = 1
    x = abs(x)
elif x == 0:
    if y < 0:
        ans = 2
        y = abs(y)
else:
    if y > 0:
        ans = 1
    else:
        ans = 2
    x = abs(x)
    y = abs(y)
print((x - 1) // l + (y - 1) // l + 2 + ans)