import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

from functools import reduce

N = int(readline())

nums = []
for S in readlines():
    S = [x - ord('0') if 0 <= x-ord('0') < 10 else x - ord('A') + 10 for x in S.rstrip()]
    D = max(S) + 1
    x = reduce(lambda x,y: D*x + y, S)
    nums.append(x)

answer = min(nums)
print(answer)