import math
import sys
def S(): return sys.stdin.readline().rstrip()
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int, sys.stdin.readline().rstrip().split())
def LI(): return list(map(int, sys.stdin.readline().rstrip().split()))
def LS(): return list(sys.stdin.readline().rstrip().split())

n = I()
s = set(["0", "1", "2", "3", "4", "5", "6", "7", "8", "9"])

for i in range(n):
    a = LS()
    if a[4] == "YES":
        s = s & set(a[0:4])
    else:
        s = s - set(a[0:4])

print(list(s)[0])