n = int(input())
nums = [str(i) for i in range(10)]
for _ in range(n):
    rnd = input().split()
    if rnd[-1] == "NO":
        for i in range(4):
            if rnd[i] in nums:
                nums.remove(rnd[i])
    else:
        for i in sorted(nums):
            if i not in rnd:
                nums.remove(i)
print(nums[0])