N = gets.to_i
W = gets.split.map(&:to_i)
s = W.inject(:+)
dp = Array.new(s / 2 + 1, false)
dp[0] = true
W.each do |w|
  (s / 2 + 1).downto(w) do |i|
    dp[i] ||= dp[i - w]
  end
end
ans = if s % 2 == 0 and dp[s / 2]
        "possible"
      else
        "impossible"
      end
puts ans