import string
import sys
from typing import Generator, List, Tuple


def input(): return sys.stdin.readline().rstrip('\n')


def cvt(x, b):
    a = 0
    for i in x:
        a = a * b + (string.digits + string.ascii_uppercase)[:b].index(i)
    return a


def main():
    n = int(input())
    a = [input() for _ in range(n)]
    for d in range(2, 37):
        try:
            return min(cvt(x, d) for x in a)
        except ValueError:
            pass


if __name__ == '__main__':
    ret = main()


    def out(x):
        if isinstance(x, List) or isinstance(x, Tuple):
            print(*x)
        else:
            print(x)


    if ret is None:
        pass
    elif isinstance(ret, Generator):
        for val in ret:
            out(val)
    else:
        out(ret)