x, y = list(map(int, input().split(' ')))
x2, y2 = list(map(int, input().split(' ')))

if (x == y and x2 == y2) or (x == x2 == 0 and y > y2) or (y == y2 == 0 and x > x2):
    print(x + 1)
else:
    print(max([x, y]))