def f(n, weights)
  sum = weights.inject(0, :+)
  return false if sum.odd?

  dp = {}
  g = lambda{|i, w|
    dp[[i,w]] ||= if w == 0
      true
    elsif i == n
      false
    elsif w < weights[i]
      g.(i+1, w)
    else
      g.(i+1, w) || g.(i+1, w-weights[i])
    end
  }
  g.(0, sum/2)
end

N = gets.to_i
W = gets.split.take(N).map(&:to_i)
puts f(N, W) ? :possible : :impossible