fun main() {
    val builder = StringBuilder()

    val n = readInputLine().toInt()

    val wArr = readInputLine().split(" ").map { it.toInt() }

    val sum = wArr.sum()

    if (sum % 2 == 1) {
        println("impossible")
        return
    }

    val dp = Array(n) { mutableSetOf<Int>() }

    dp[0].add(0)
    dp[0].add(wArr[0])

    for (i in 1 until wArr.size) {
        dp[i].addAll(dp[i - 1])
        for (prev in dp[i - 1]) {
            dp[i].add(prev + wArr[i])
        }
    }

    builder.appendln(if (dp[n - 1].contains(sum / 2)) "possible" else "impossible")

    print(builder.toString())
}

fun readInputLine(): String {
    return readLine()!!
}