c2n = {chr(ord('0') + i): i for i in range(10)}
c2n.update({chr(ord('A') + i): i + 10 for i in range(26)})

def read_data():
    N = int(input())
    Vs = [input() for _ in range(N)]
    return Vs

def solve(Vs):
    min_n = float('inf')
    for v in Vs:
        n = convert(v)
        if n < min_n:
            min_n = n
    return min_n

def convert(v):
    v = v.lstrip('0')
    if len(v) == 0:
        return 0
    nums = [c2n[c] for c in v]
    base = max(nums) + 1
    n = 0
    for num in nums:
        n *= base
        n += num
    return n

Vs = read_data()
print(solve(Vs))