X = int(input())
Y = int(input())
L = int(input())

def PositionCounter(XY):
    cnt = 0

    if XY < 0 :
        XY *= -1
        cnt += 1

    Syo = XY // L
    Amari = XY % L

    if Amari == 0:
        cnt = cnt + Syo * 1
    else:
        cnt = cnt + (Syo * 1) + 1

    return cnt

print(PositionCounter(X) + PositionCounter(Y))