# -*- coding: utf-8 -*-

N = int(input())
V = []
a = list('0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ')
c = []

for i in range(N):
    V = input()
    number = 0

    # 最小のｎ進数を探す
    for j in V:
        if number <= a.index(j)+1:
            number = a.index(j)+1

    n = 0
    for k in range(len(V)):
        n += a.index(V[-1-k]) * (number ** k)
    c.append(n)

print(min(c))