import math
X = int(input())
Y = int(input())
L = int(input())

x = math.ceil(abs(X)/L)
y = math.ceil(abs(Y)/L)

if X != 0 and Y > 0:
    r = 1
elif Y < 0:
    r = 2
elif X == 0 and Y >= 0:
    r = 0
elif X != 0 and Y == 0:
    r = 1
print(x+y+r)