def main():
    X = int(input())
    Y = int(input())
    L = int(input())

    if X == Y == 0:
        print(0)
        return

    if X == 0 and Y > 0:
        direc = 0
    elif Y >= 0:
        direc = 1
    else:
        direc = 2

    dist = (abs(X) + L - 1) // L
    dist += (abs(Y) + L - 1) // L

    print(direc + dist)

main()