#https://yukicoder.me/submissions/219740から書き換え
ans = set("0123456789")
n = int(input())
for i in range(n):
	nums, r = input().rsplit(None, 1)
	nums = set(nums)
	if r == "YES":
		ans &= nums	
	else:
		ans -= nums
print("".join(ans))