X = int(input())
Y = int(input())
L = int(input())
Destination = list([X,Y])

def PositonJudge(Destination,L):
    cnt = 0
    Syo = 0
    Amari = 0

    if Destination[0] < 0 and Destination[1] < 0:
        cnt += 2
    elif (Destination[0] != 0) or (Destination[1] < 0):
        cnt += 1

    if Destination[0] < 0:
        Destination[0] *= -1
    if Destination[1] < 0:
        Destination[1] *= -1

    for i in range(2):
        Syo = Destination[i] // L
        Amari = Destination[i] % L
        if Amari > 0:
            cnt += 1
        cnt += Syo

    print(cnt)

PositonJudge(Destination,L)