import scala.annotation.tailrec
import scala.io.StdIn

object Main extends App {

  val mod: Int = Math.pow(10, 9).toInt + 7

  def proc(n: Int): Int = {

    if (n == 1) return 1

    @tailrec
    def rec(cnt: Int, a: Long, b: Long, c: Long): Long = {
      if (cnt <= 2) {
        (a + b + c) % mod
      } else {
        rec(cnt - 1, c, (a + c) % mod, b)
      }
    }

    rec(n, 1, 1, 0).toInt
  }

  val n = StdIn.readInt()
  val result = proc(n)
  println(result)
}