void kaprekarNumbers(int p, int q)
{
    var hasModifiedKaprekarNum = false;

    while (p <= q)
    {
        var squareNumStr = ((long)Math.Pow(p, 2)).ToString();

        var rightStrCnt = squareNumStr.Length % 2 == 0 ? squareNumStr.Length / 2 : squareNumStr.Length / 2 + 1;
        var leftStrCnt = squareNumStr.Length - rightStrCnt;

        var leftNum = leftStrCnt != 0 ? long.Parse(squareNumStr.ToString().Substring(0, leftStrCnt)) : 0;
        var rightNum = long.Parse(squareNumStr.ToString().Substring(leftStrCnt, rightStrCnt));

        if (leftNum + rightNum == p)
        {
            Console.Write($"{p} ");
            hasModifiedKaprekarNum = true;
        }

        p++;
    }

    if (!hasModifiedKaprekarNum) Console.WriteLine("INVALID RANGE");
}