n = input()
m = n.split()
a = int(m[0])
b = int(m[1])
count = 0
if b < 23 or a > 25:
    count = 3
elif 23 <= a and b <= 25:
    count = 2 - (b - a)
elif a <= 23 and b >= 23 and b <= 25:
    count = 25 - b
elif a >= 23 and a <= 25 and b >= 25:
    count = a - 23
print(str(count))