n = gets.to_i
w = gets.split.map(&:to_i)
total = w.sum

if total % 2 == 1
    puts "impossible"
    exit 0
end

dp = [false] * (total / 2 + 1)
dp[0] = true

w.each do |wi|
    (0..(dp.size-1)).to_a.reverse.each do |num|
        dp[wi+num] = true if wi + num <= total / 2 && dp[wi]
    end
end

puts dp[total/2] ? "possible" : "impossible"