N = int(input())
a= [input().split() for _ in range(N)]
s = set()
k = set([i for i in range(10)])
for i in range(N):
    if a[i][4] == "NO":
        s.add(int(a[i][0]))
        s.add(int(a[i][1]))
        s.add(int(a[i][2]))
        s.add(int(a[i][3]))
    else:
        b = set()
        b.add(int(a[i][0]))
        b.add(int(a[i][1]))
        b.add(int(a[i][2]))
        b.add(int(a[i][3]))
        k = k.intersection(b)

if len(k) == 1:
    for i in k:
        print(i)
        exit()
for i in range(10):
    if not i in s and i in k:
        print(i)
        exit()