fun main(args: Array<String>){
    val weightCount = readLine()!!.toInt()
    weightList = readLine()!!.split(" ").map { it.toInt() }
    totalWeight = weightList.sumBy { it }
    val ans = if(getAns(0, 0)) "possible" else "impossible"
    println(ans)
}

var weightList = listOf<Int>()
var totalWeight = 0
val dic = mutableMapOf<Int, MutableMap<Int, Boolean>>()

fun getAns(pos:Int, subTotal:Int):Boolean {
    if(subTotal * 2 == totalWeight) {
        return true
    }
    if(subTotal * 2 > totalWeight) {
        return false
    }
    if(pos > weightList.lastIndex) {
        return false
    }
    if(!dic.containsKey(pos)) {
        dic[pos] = mutableMapOf()
    }
    dic[pos]!![subTotal]?.let {
        return it
    }

    val ret1 = getAns(pos + 1, subTotal)
    val ret2 = getAns(pos + 1, subTotal + weightList[pos])

    dic[pos]!![subTotal] = (ret1 || ret2)
    return (ret1 || ret2)
}