import scala.math._
import scala.collection.mutable._
import scala.collection.immutable._

object Main{
  def main(args: Array[String]): Unit = {
    val sc = new java.util.Scanner(System.in)
    val pw = new java.io.PrintWriter(System.out)

    val n = sc.nextInt
    val ms = Array.fill(n)(sc.nextInt)

    val bit = new BIT(30000)
    val c = ms.reverse.map(m => {
      val a = bit.get(m);
      bit.update(m, 1)
      a
    }).sum

    pw.println(c);
    pw.flush()
  }
}

class BIT(val n: Int){
  private var tree: Array[Int] = Array.fill(n+1)(0) //1-index (1..n)
  def init(): Unit = {tree = Array.fill(n+1)(0)}
  def update(x: Int, a: Int): Unit = {
    var i: Int = x
    while (i <= n){tree(i) = tree(i) + a; i += (i &  (-i))}
  }
  def get(x: Int): Int = {
    var i: Int = x
    var a: Int = 0
    while (i > 0){a += tree(i); i -= (i & (-i))}
    a
  }
  def lower_bound(i: Int): Int = {
    var w = i
    var k: Int = 1
    var x: Int = 0
    while (k*2 <= n) k *= 2
    while (k > 0){
      if (x+k <= n && tree(x+k) < w) {w -= tree(x+k); x += k}
      k /= 2
    }
    x+1
  }
}