# No.773 コンテスト
a, b = [int(i) for i in input().split()]

if a > 25 or b < 23:
    perticipate = 3
elif a <= 23 and b >= 25 :
    perticipate = 0
elif a < 23 and 23 <= b <= 25:
    perticipate = 25 - b
elif 23 <= a <= 25 and 23 <= b <= 25:
    perticipate = 3 - (b - a)
elif 23 <= a <= 25 and b > 25:
    perticipate =  a - 23

print(perticipate)