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

'''
'1' == 49 -> 2進数
'9' == 57 -> 10進数
'A' == 65 -> 11進数
'Z' == 90 -> 36進数
'''

N = int(input())
V = []
for i in range(N):
    V.append(input())

min_int = -1
for v in V:
    max_chr = -1
    for c in v:
        max_chr = max(ord(c), max_chr)
    base = max_chr-47 if max_chr<=57 else max_chr-54
    decimal = 0
    for c,i in zip(v, range(len(v)-1, -1, -1)):
        dec_digit = ord(c)-48 if ord(c)<=57 else ord(c)-55
        decimal += pow(base, i) * dec_digit
    min_int = decimal if min_int==-1 else min(min_int, decimal)

print(min_int)