import math

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

a =  math.ceil(abs(x) / l)
b =  math.ceil(abs(y) / l)

if y == 0:
    if x == 0:
        c = 0
    else:
        c = a + 1

elif y > 0:
    if x == 0:
        c = b
    else:
        c = a + b + 1

else:
    c = a + b + 2

print(c)