f=lambda:int(input())
x=f()
y=f()
l=f()
g=lambda t:abs(t)//l+1 if t%l else abs(t)//l
if y>0:
	if x==0:
		k=0
	else:
		k=1
elif y<0:
		k=2
elif x==0:
	k=0
else:
	k=1
print(g(x)+g(y)+k)