object Main {

    def main(args: Array[String]): Unit = {
      import scala.io.StdIn._
      val N = readLine().toLong

      val start = Math.floor((1 + Math.sqrt(4 * N + 1))/2).toLong

      def rec(m: Long, acm: Long): Long =
        if (m < N) {
          if ((N / m) == (N % m)) rec(m + 1, acm + m)
          else rec(m + 1, acm)
        } else acm

      println(rec(start, N))
    }

}
