#!/usr/bin/python
# -*- coding: utf-8 -*-

ans = set(["0","1","2","3","4","5","6","7","8","9"])
N = int(raw_input())

for i in range(N):
       	arys = map(str,raw_input().split())
       	flag = arys.pop(-1)
       	if flag == "YES":
       		ans &= set(arys)
       	else: ###NO
       		ans -= set(arys)
print list(ans)[0]