n = int(input())
yes = []
no = []
ans = set(['0', '1', '2', '3', '4', '5', '6', '7', '8', '9'])
for _ in range(n):
    a, b, c, d, r = input().split()
    l = [a, b, c, d]
    if r == 'NO':
        for i in l:
            no.append(i)
    else:
        yes.append(l)

for i in yes:
    ans = ans & set(i)

ans = list(ans)
no = list(set(no))

if len(ans) == 1:
    print(ans[0])
    exit()
else:
    for j in no:
        if j in ans:
            ans.remove(j)

print(ans[0])