from string import ascii_uppercase, digits
import sys
input = sys.stdin.readline
sys.setrecursionlimit(10 ** 7)
inf = 10**20

char = digits+ascii_uppercase
stoi = {s: i for i, s in enumerate(char)}


def convert(S, d):
    res = 0
    for s in S:
        res = d * res + stoi[s]
    return res


N = int(input())
V = [input().rstrip() for _ in range(N)]

ans = inf
for v in V:
    vmax = max(v)
    for i, c in enumerate(char[1:], 2):
        if vmax <= c:
            ans = min(ans, convert(v, i))

print(ans)