import java.io.PrintWriter
import java.util.Scanner
import scala.annotation.tailrec

object Main extends App {
  val sc = new Scanner(System.in)
  val out = new PrintWriter(System.out)
  
  def solve(): String = {
    val N = sc.nextInt
    val W = Array.fill(N)(sc.nextInt)
    val MaxW = 10010
    val dp = Array.ofDim[Boolean](MaxW)
    dp(0) = true
    for (i <- 0 until N)
      for (j <- 0 until MaxW - W(i) if dp(j))
        dp(j+W(i)) = true

    val sum = W.sum
    if (sum % 2 == 0 && dp(sum/2)) "possible"
    else "impossible"
  }
  
  out.println(solve)
  out.flush
}