N = gets.to_i
weights = gets.split.map(&:to_i)
size = N * 100

dp = Array.new(size + 1, false)
sum = 0
dp[0] = true
N.times do
  w = weights.shift
  sum += w

  size.downto(0) do |i|
    if dp[i]
      dp[i + w] = true
    end
  end
end

if sum % 2 == 0 && dp[sum / 2]
  puts "possible"
else
  puts "impossible"
end