import math

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

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

if y >= 0:
    if x == 0:
        c += 0
    else:
        c += 1
else:
    c += 2

print(c)