import sys
input=lambda: sys.stdin.readline().rstrip()
n=int(input())
A=[[str(i) for i in input().split()] for _ in range(n)]
Ans=[True]*10
for i in range(n):
  if A[i][4]=="NO":
    for j in range(4):
      Ans[int(A[i][j])]=False
  else:
    S=set()
    for j in range(4):
      S.add(int(A[i][j]))
    for j in range(10):
      if j not in S:
        Ans[j]=False
for i in range(10):
  if Ans[i]:
    print(i)
    break