def main():
    EW = int(input())
    NS = int(input())
    v  = int(input())

    ans = round(abs(NS)/v)
    ans = ans + round(abs(EW)/v)

    if not( EW%v == 0):ans += 1
    if not( NS%v == 0):ans += 1

    if not(EW == 0) :ans += 1
    if NS < 0 and EW == 0:
        ans +=2
    elif NS < 0:
        ans +=1

    print(ans)

if __name__=="__main__":
    main()