N = int(input())
nums = ["0","1","2","3","4","5","6","7","8","9"]

for i in range(N):
    l = list(input().split())
    if l[-1] == "YES":
        temp = []
        for item in l:
            if item in nums:
                temp.append(item)
        nums = temp
    else:
        for j in l:
            if j in nums:
                nums.remove(j)

print(int(nums[0]))