N = int(input())
inp = []
for i in range(N):
    inp.append(input().split())
    
cards = list('0123456789')
pos = []

for t in inp:
    isIn = t.pop(-1)
    if isIn == "NO":
        for n in t:
            if n in cards:
                cards.remove(n)
            else:
                break
    else:
        common = list(set(t) & set(pos))
        if common:
            pos = common
        else:
            pos.extend(t)
        pos = list(set(pos))
        
if len(set(cards) & set(pos)) == 1:
    ans = list(set(cards) & set(pos))[0]
else:
    ans = cards[0]
  
print(ans)