object Main extends App {

  import scala.io.StdIn._

  solve
  def solve:Unit = {
    val n = readInt
    if (n == 0) return
    val self = readLine.trim.split(' ').map(_.toInt).sorted.reverse
    val other = readLine.trim.split(' ').map(_.toInt).sorted.reverse
    self.indices.find{j ⇒
      val i = upperBound(other, self(j))
      j + 1 > 2 * i
    } match {
      case Some(i) if i + 1 < n ⇒ println(i + 1)
      case _ ⇒ println("NA")
    }
    solve
  }
  def upperBound(array: Array[Int], target: Int): Int = {
    var left = 0
    var right = array.length
    while(left < right){
      val mid = (left + right) / 2
      if (array(mid) >= target){
        left = mid + 1
      }else {
        right = mid
      }
    }
    right
  }
  implicit class Extension[T](val value :T) extends AnyVal {
    @inline
    def let[A](@inline func: T ⇒ A): A = func(value)
    @inline
    def also(@inline func: T ⇒ Unit): T = {func(value); value}
  }
}
