n=STDIN.gets.to_i
bs=STDIN.gets.split(" ")

dp=Array.new(10002,0)
dp[0]=1
sum=0
bs.each do |e|
	e1=e.to_i
	sum+=e1
	(10000-e1).downto(0) do |i|
		if dp[i]==1 then
			dp[i+e1]=1
		end
	end
end
if sum%2==0 && dp[sum/2]==1 then
	puts "possible"
else
	puts "impossible"
end