require 'pp'

$ws = []
$n = 0
$dp = {}

def main
  $n = gets.to_i
  $ws = gets.strip.split(' ').map{|e| e.to_i}
  $n.times{|i| $dp[i] = {}}
  sum = $ws.reduce(:+)
  result = solve(0, 0, sum)
  puts result ? "possible" : "impossible"
end

def solve(i, acc, sum)
  if (i === $n)
    return false
  end
  if $dp[i].key?(acc)
    return $dp[i][acc]
  end
  if (sum % 2 === 1)
    return false
  end
  if (acc * 2 === sum)
    return true
  end
  nex = $ws[i]
  result = solve(i + 1, acc + nex, sum) || solve(i + 1, acc, sum)
  $dp[i][acc] = result
end

main()