import kotlinx.coroutines.*
import kotlinx.coroutines.channels.*

suspend fun sum(s: List<Int>, c: Channel<Int>) {
    var sum = 0
    for (v in s) {
        sum += v
    }
    c.send(sum)
}

fun main() = runBlocking {
    val s = listOf(7, 2, 8, -9, 4, 0)
    
    val c = Channel<Int>()
    launch { sum(s.subList(s.size / 2, s.size - 1), c) }
    launch { sum(s.subList(0, s.size / 2), c) }
    
    val x = c.receive()
    val y = c.receive()
    
    println("$x + $y = ${x + y}")
}