turns = int(input())

maybe_true_set = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'}
false_set = set()

for _ in range(turns):
    turn = input().split()
    answer = turn[-1]
    numSet = set(turn[0:4])

    if answer == 'NO':
        false_set = numSet.union(false_set)

    else:
        maybe_true_set = numSet.intersection(maybe_true_set)

print(maybe_true_set.difference(false_set).pop())