import math
x = int(input())
y = int(input())
c = int(input())
cou = 0
if y >= 0 and x == 0:
    cou += 0
elif y >= 0 and x != 0:
    cou += 1
elif y < 0:
    cou += 2
a = math.ceil((abs(x)+abs(y))/c)
print(a+cou)