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

  dp = {}
  dp[0] = true
  weights.each{|weight|
    (sum/2).downto(0){|w|
      dp[w] ||= dp[w-weight]
    }
  }
  dp[sum/2]
end

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