class Yukicoder
  def initialize
    n = gets.chomp.to_i
    w = gets.chomp.split.map(&:to_i).sort
    sum = w.inject(:+)

    hash = Hash.new(false)

    w.each do |num|
      temp = hash.dup

      hash.each do |k,v|
        temp[k+num] = true
      end

      hash = temp.dup
      hash[num] = true
    end

    if sum.even? && hash[sum/2]
      puts "possible"
    else
      puts "impossible"
    end
  end
end

Yukicoder.new