Nim game

You are encouraged to solve this task according to the task description, using any language you may know.
Nim is a simple game where the second player ─── if they know the trick ─── will always win.



The game has only 3 rules:

   start with   12   tokens
   each player takes   1,  2,  or  3   tokens in turn
  the player who takes the last token wins.


To win every time,   the second player simply takes 4 minus the number the first player took.   So if the first player takes 1,   the second takes 3 ─── if the first player takes 2,   the second should take 2 ─── and if the first player takes 3,   the second player will take 1.



Task

Design a simple Nim game where the human player goes first, and the computer always wins. The game should enforce the rules.




// Version 1.3.21
 
fun showTokens(tokens: Int) {
    println("Tokens remaining $tokens\n")
}
 
fun main() {
    var tokens = 12
    while (true) {
        showTokens(tokens)
        print("  How many tokens 1, 2 or 3? ")
        var t = readLine()!!.toIntOrNull()
        if (t == null || t < 1 || t > 3) {
            println("\nMust be a number between 1 and 3, try again.\n")
        } else {
            var ct = 4 - t
            var s = if (ct > 1) "s" else ""
            println("  Computer takes $ct token$s\n")
            tokens -= 4
        }
        if (tokens == 0) {
            showTokens(0)
            println("  Computer wins!")
            return
        }
    }
}