x, y ,l= int(input()), int(input()),int(input())
turn = 0
if(y < 0):
    turn+=2
else:
    turn+=1
if(abs(y)%l==0):
    turn+=abs(y)//l
else:
    turn+=abs(y)//l+1
if(abs(x)%l==0):
    turn+=abs(x)//l
else:
    turn+=(abs(x)//l+1)
if(x==0):
    turn-=1
print(turn)