def convert(_s, base):
    ans = 0
    _s.reverse()
    for i, s in enumerate(_s):
        if s.isalpha():
            ans += base**i * (ord(s) - ord("A") + 10)
        else:
            ans += base**i * int(s)
    return ans

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

ans = 36**13
for i in nums:
    largest_char = sorted(i, reverse=True)[0]
    base = 10
    if largest_char.isalpha():
        base = ord(largest_char) - ord("A") + 11
    else:
        base = int(largest_char) + 1
    ans = min(ans, convert(list(i), base))
print(ans)