def convert(s, base):
    global dic
    ans = 0
    for i in s:
        ans *= base
        ans += dic[i]
    return ans

N = int(input())
nums = [input() for i in range(N)]

dic = {chr(ord("0")+i):i for i in range(10)}
for i in range(ord("Z")-ord("A")):
    dic[chr(ord("A")+i)] = i + 10
ans = 36**13
for i in nums:
    largest_char = sorted(i, reverse=True)[0]
    base = dic[largest_char] + 1
    ans = min(ans, convert(list(i), base))
print(ans)