#!/usr/bin/python2
# -*- coding: utf-8 -*-
# †
import string

# 基数変換. {base}進数で表現された{s}を10進数にします。
#base2int = lambda s, base: int(s, base)
def base2int(s, base, digits=string.digits+string.ascii_uppercase):
    if len(s) == 0:
        return 0
    is_negative = s[0] == '-'
    if is_negative:
        s = s[1:]
    num = 0
    for c in s:
        num *= base
        num += digits.index(c)
    if is_negative:
        num *= -1
    return num


D = string.digits + string.ascii_uppercase
n = int(raw_input())
mini = float('inf')
for _ in xrange(n):
    s = raw_input()
    base = max(D.find(ch) + 1 for ch in s)
    mini = min(mini, base2int(s, base))
print mini