import math

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

distance = 0

if X != 0:
    distance += math.ceil(abs(X) / L)

if Y != 0:
    distance += math.ceil(abs(Y) / L)

if X != 0 or Y != 0:
    distance += 1
    
if Y < 0:
    distance += 1

print(distance)