N = int(input())
Args = [input().split() for i in range(N)]
candidate = [ str(i) for i in range(10)]

for arg in Args:
    if arg[4] == 'YES':
        candidate = list(set(arg[:-1]).intersection(set(candidate)))
    if arg[4] == 'NO':
        candidate = list(set(candidate).difference(set(arg[:-1])))
    if len(candidate) == 1:
        break
        
print(candidate[0])