MAX_N = 10
MAX_W = 10

def main
  n = gets.to_i
  w_list = gets.split.map(&:to_i)
  w_sum = w_list.inject(:+)
  return "impossibie" if w_sum % 2 == 1

  dp = [false] * (MAX_N * MAX_W + 1)
  dp[0] = true

  w_list.each do |w|
    (MAX_N * MAX_W - w).downto(0) do |i|
      dp[i+w] = true if dp[i]
    end
  end

  if dp[w_sum/2] 
    return "possible" 
  else 
    return "impossibie"
  end
end

p main()