N = int(input())

def convert(s):
    if 65 <= ord(s) <= 90:
        return ord(s) - 65 + 10
    return int(s)

ansl = []
for i in range(N):
    v = list(input())
    a = list(map(lambda x: convert(x), v))
    m = max(a)
    base = m + 1
    # base 進数として考える
    keta = 1
    ans = 0
    for aa in a[::-1]:
        ans += aa * keta
        keta *= base
    ansl.append(ans)

print(min(ansl))