import math

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


if x == 0:
    if y > 0:
        count = math.ceil(y/l)
    else:
        count = math.ceil(abs(y)/l)
elif y == 0:
    count = 1 + math.ceil(abs(y)/l)
elif y > 0:
    count = 1 + math.ceil(abs(x)/l) + math.ceil(abs(y)/l)
else:
    count = 2 + math.ceil(abs(x)/l) + math.ceil(abs(y)/l)
print(count)