n = int(raw_input())
yes = set(range(10))
no = set()

for _ in range(n):
	num, r = raw_input().rsplit(" ",1)
	if r == "YES":
		yes = yes & set(map(int,num.split()))
	else:
		no = no | set(map(int,num.split()))

yes = yes - no
print yes.pop()