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) true
        else (index + 1 until W.size).any { search(it, currentSum) }
    }

    if (search(0, 0)) {
        println("possible")
    } else {
        println("impossible")
    }
}