package yukicoder

fun main() {
    val N: Int = 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
    val sortedW = W.sortedDescending()
    var sumW = 0
    for (currentW in sortedW) {
        if (sumW + currentW <= halfW) {
            sumW += currentW
        }
    }
    if (halfW == sumW) {
        println("possible")
    } else {
        println("impossible")
    }
}