N = int(input())
ans = [True]*(10)
for i in range(N):
    ls = list(map(str,input().split()))
    if ls[-1] == 'NO':
        for j in range(4):
            ans[int(ls[j])] = False
    else:
        lsall = list(range(10))
        for j in range(4):
            lsall.remove(int(ls[j]))
        for k in lsall:
            ans[k] = False
print(ans.index(True))