package yukicoder

fun main() {
    readLine()!!.toInt()
    val W: List<Int> = readLine()!!.split(" ").map(String::toInt)

    val sum: Int = W.sum()
    if (sum % 2 != 0) {
        println("impossible")
        return
    }

    val halfW = sum / 2

    fun search(index: Int, sum: Int): Boolean {
        val currentSum = sum + W[index]
        return if (currentSum > halfW) {
            false
        } else if (currentSum == halfW) {
            true
        } else {
            for (i in index + 1 until W.size) {
                if (search(i, currentSum)) {
                    return true
                }
            }
            return false
        }
    }

    when (search(0, 0)) {
        true -> println("possible")
        false -> println("impossible")
    }
}