number = [True, True, True, True, True, True, True, True, True, True]

def listchange(inpt):
	if inpt[4] == 'YES':
		for i in range(0, 10):
			if not(str(i) in inpt):
				number[i] = False
	else:
		for i in range(0, 4):
			number[int(inpt[i])] = False

n = int(raw_input())

for i in range(0, n):
	inpt = raw_input().split()
	listchange(inpt)

for i in range(0, 10):
	if number[i]:
		print i
		break