n = int(input())
K = [input().split(' ') for _ in range(n)]

q = set()

M = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'}
Y = []

for i in range(n):
    if K[i][4] == "NO":
        q |= set(K[i][:4])
    elif K[i][4] == "YES":
        Y = K[i][:4]
        M = M & set(Y)

L = M - q
print(L.pop())