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

def move(X, Y, L):
	if X == 0:
		x_count= 0
	else:
		x_count= (abs(X) + L - 1) // L +1
	if Y > 0:
		y_count= (Y + L - 1) // L
	elif Y == 0:
		y_count= 0
	elif X != 0 and Y < 0:
		y_count= (abs(Y) + L - 1) // L +1
	else:
		y_count= (abs(Y) + L - 1) // L +2
	
	return print(x_count+y_count)

move(X, Y, L)