n = int(input())
input_lst = [ input().split(' ') for i in range(n) ]

answer_de = {
    0: True,
    1: True,
    2: True,
    3: True,
    4: True,
    5: True,
    6: True,
    7: True,
    8: True,
    9: True,
}

answer_in = {
    0: True,
    1: True,
    2: True,
    3: True,
    4: True,
    5: True,
    6: True,
    7: True,
    8: True,
    9: True,
}

for input in input_lst:
    if input[4] == 'NO':
        for num in input[:-1]:
            answer_de[int(num)] = False
    else:
        for key in answer_in.keys():
            if str(key) in input[:-1] and answer_in[key]:
                continue
            else:
                answer_in[key] = False
                
for i in range(10):
    if answer_de[i] and answer_in[i]:
        print(i)
        break