class Yukicoder
  LIST = [*('0'..'9')] + [*('A'..'Z')]

  def initialize
    n = gets.chomp.to_i
    min_value = Float::INFINITY

    n.times do
      str = gets.chomp

      e = str.chars.map{|ch| LIST.index(ch)}.max
      min_value = [min_value, encode(str, e+1)].min
    end

    puts min_value
  end

  def encode(str, e)
    str.to_i(e)
  end
end

Yukicoder.new