N = gets.to_i
@w_list = gets.chomp.split.map(&:to_i)
@half = 0
@dp = Array.new(10001, false)

def main
  total = @w_list.inject(:+)

  return "impossible" if total & 1 == 1

  @half = total >> 1
  @dp[0] = true

  @w_list.each do |w|
    (@dp.size - 1).downto(0) do |i|
      @dp[i+w] = true if @dp[i]
    end
  end

  return @dp[@half] ? "possible" : "impossible"
end

puts main()