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

  dp = {}
  g = lambda{|i, w|
    return true if w == 0
    return false if i >= n || w < 0
    # nilは偽なのでhash||=じゃダメ
    return dp[[i,w]] if !dp[[i,w]].nil?

    dp[[i,w]] = g.(i+1, w) || g.(i+1, w-weights[i])
  }
  g.(0, sum/2)
end

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