import math

X, Y, L = [ int(input()) for i in range(3) ]

order = 0

if (Y,X) == (0,0):
    print(order)
    exit()

if Y > 0 and X == 0:
    o_D = 0
else:
    if Y >= 0:
        o_D = 1
    else:
        o_D = 2

if Y == 0:
    o_Y = 0
else:
    if abs(Y) > L:
        o_Y = math.ceil(abs(Y)/L)
    else:
        o_Y = 1
        
if X == 0:
    o_X = 0
else:
    if abs(X) > L:
        o_X = math.ceil(abs(X)/L)
    else:
        o_X = 1

print(o_D + o_Y + o_X)