import re

filename = 'input.txt'

expressions = []
truths = set()

with open(filename) as file:
    lines = file.readlines()
    lines_count = len(lines)

    for i in range(lines_count):
        line = lines[i]
        if i < lines_count - 2:
            bools = re.findall('[A-Z]', line)
            operators = re.findall(r'\|\||&&', line)

            if len(bools) - len(operators) != 2:
                raise ValueError('Invalid expression on line #' + str(i + 1))

            expr = dict(bools=bools, operators=operators)
            expressions.append(expr)
        elif i == lines_count - 1:
            truths = set(re.findall('[A-Z]', line))

while True:
    no_changes = True

    for expr in expressions:
        left = expr['bools'][0] in truths

        for i in range(len(expr['operators'])):
            op = expr['operators'][i]
            right = expr['bools'][i + 1] in truths
            if op == '&&':
                left = left and right
            else:
                left = left or right

        if left and expr['bools'][-1] not in truths:
            truths.add(expr['bools'][-1])
            no_changes = False
            break
    if no_changes: break

print(sorted(truths))