lm = lambda x: x - 55 if x >= 65 else x - 48
n = int(input())
e = [[int(lm(ord(i))) for i in list(input())] for i in range(n)]

ans = -1
for ee in e:
    num_base = max(ee) + 1
    t = 0
    num = 0
    for ee2 in reversed(ee):
        t += (num_base ** num) * ee2
        num += 1
    ans = min(ans, t) if ans >= 0 else t
print(ans)