object mainRun {
  def main(args: Array[String]): Unit = {
    val a = (new dataStr).take(45697600)
    a.grouped(100).grouped(1000).foreach(println)
  }

  class dataStr extends Iterator[String] {
    private val itr: Iterator[BigInt] = Iterator.iterate(0:BigInt)(_ + 1)
    private val alpha = ('A' to 'Z').toList
    private val digits = ('0' to '9').toList

    override def hasNext = true
    override def next = {
      val na = itr.next; val ca: Char = ('A' + na%26).toChar
      val nb = if(na/26 < 26) BigInt(0) else na/26;   val cb: Char = ('A' + (na/26)%26).toChar
      val nc = nb/26; val cc: Char = digits(nc.toInt%10)
      val nd = nc/10;  val cd: Char = ('A' + ((nc/10)%26)).toChar
      val ne = nd/26;   val ce: Char = digits(ne.toInt%10)
      val nf = ne/10; val cf: Char = ('A' + (ne/10)%26).toChar
      s"$cf$ce$cd$cc$cb$ca"
    }
  }
}