x, y = map(int,input().split())
x1, y1 = map(int,input().split())

if x == y and x1 == y1 and x1 < x:
    if x * x1 >= 0 and y * y1 > 0:
        print(x + 1)
    else:
        print(max(x, y))
else:
    print(max(x, y))