n = gets.to_i
w_list = gets.split.map(&:to_i)
sum = w_list.inject(:+)
dp = Array.new(10001, 0)
dp[0] = 1
w_list.each do |w|
  (10000 - w).downto(0) do |i|
    dp[i + w] = 1 if dp[i] == 1
  end
end
puts dp[sum / 2] == 1 && sum.even? ? 'possible' : 'impossible'