def main():
    x, y = map(int, input().split())
    x2, y2 = map(int, input().split())

    straight = abs(x-y)
    slanted = min(x, y)
    if straight == 0 and x2 == y2 and x > x2:
        print(slanted + 1)
    else:
        print(straight + slanted)


if __name__ == "__main__":
    main()