kotline increament and decrement operator

fun main(args:Array<String>)
{
    var firstno=8    var secno=3
    var incre=firstno+1    var dec=firstno-1          println(incre)
    println(++firstno)

    println(dec)
    println(--firstno)
}

• OUTPUT >> 
• 9
• 9
• 7
• 8