x=int(input())
y=int(input())
l=int(input())
ans=0

if x != 0:
    ans+=1+(abs(x)-1)//l+1

if y != 0:
    ans+=(abs(y)-1)//l+1
    if y<0 and x ==0:
        ans+=2
    elif y<0:
        ans+=1
print(ans)