def f(X):
    Y = (abs(X)+L-1) // L
    return Y


X, Y, L = [int(input()) for _ in range(3)]

cnt = 0
if Y >= 0:
    cnt += f(X) + f(Y)
    cnt += 1
    if X == 0:
        cnt -= 1

elif Y < 0:
    cnt += f(X) + f(Y)
    cnt += 2

print(cnt)