N = gets.to_i
@w_list = gets.chomp.split.map(&:to_i)
@half = 0
@dp = Array.new(100, Array.new(10001, true))

def solve(idx, total)
  return false if idx >= N || total > @half
  return @dp[idx][total] if @dp[idx][total] == false

  new_total = total + @w_list[idx]
  return true if new_total == @half

  return true if solve(idx + 1, total) || solve(idx + 1, new_total)
  return @dp[idx][total] = false
end

def main
  total = @w_list.inject(:+)

  return "impossible" if total & 1 == 1

  @half = total >> 1
  @w_list.sort!

  return solve(0, 0) ? "possible" : "impossible"
end

puts main()