'''
if p is the probability that the player win, then expectation of banker's income will be
probability     p       1 - p
income          -n      1
E = 1 - p - pn = 1 - (n + 1)p > 0
so bonus = n + 1 < 1 / p
'''

def p_trace(loop):
    base = 2
    p_lst = [1]
    for l in range(loop):
        p = 1 / base
        left = list(map(lambda x: x * p, p_lst)) + [0]
        right = [0] + list(map(lambda x: x * (1 - p), p_lst))
        p_lst = list(map(lambda x: x[0] + x[1], zip(left, right)))
        base += 1
    return sum(p_lst[:len(p_lst) // 2])

print(int(1 / p_trace(15)))