A = ["0","1","2","3","4","5","6","7","8","9"]
B = []
N = int(input())
ans = 0
for i in range(N):
    X = input().split()
    for c in range(4):
        if X[-1] == "NO":
            if X[c] in A:
                A.remove(X[c])
            elif X[c] in B:
                B.remove(X[c])
        else:
            if X[c] in A:
                B.append(X[c])
if len(A) == 1:
    print(A[0])
elif len(B) == 1:
    print(B[0])
else:
    for i in range(len(B)):
        if B.count(B[i]) != 1:
            ans = B[i]
    print(ans)