S = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"

min = nil

gets
while line = gets do
  36.downto(2) do |r|
    s = line.chomp
    break unless s =~ /^[0-#{S[r-1]}]+$/
    v = s.to_i(r)
    min = v if !min || v < min
  end
end

puts min