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