def recursive(left, right, remain, weights)
  if remain == 0
    return left == right
  end

  if (left - right).abs > remain
    return false
  end

  w = weights.shift

  result_left = recursive(left + w, right, remain - w, weights)
  if result_left
    weights.unshift(w)
    return result_left
  end

  result_right = recursive(left, right + w, remain - w, weights)
  weights.unshift(w)
  return result_right
end

N = gets.to_i
weights = gets.split.map(&:to_i)

remain = weights.sum
result = recursive(0, 0, remain, weights)

if result
  puts "possible"
else
  puts "impossible"
end