import kotlin.math.abs

// editorial
fun main() {
    val n = readLine()!!.toInt()
    var a = readLine()!!.split(" ").map { it.toLong() }
    if (a.sum() < 0) {
        a = a.map { -it }
    }
    a = a.sortedDescending()
    var (x, y) = listOf(0L, 0L)
    for (i in a.indices) {
        if (i % 2 == 0) x += a[i]
        else y += a[i]
    }
    println(abs(x) - abs(y))
}