X, Y, L = int(raw_input()), int(raw_input()), int(raw_input())
order = 0
currentPosition = (0, 0)
def countTurn(x, y):
    global order
    if  currentPosition == (x, y):
        order = 0
    else:
        if x == 0 and y > 0:
            order = 0
        else:
            if y >= 0:
                order += 1
            else:
                order += 2
def countMoveFoward(n):
    global order
    n = abs(n)
    if n != 0:
        if n <= L:
            order += 1
        else:
            if n % L == 0:
                order += n/L
            else:
                order += n/L + 1
    pass
countTurn(X, Y)
countMoveFoward(X)
countMoveFoward(Y)
print order