using System;
using System.Linq;

namespace _03.Inversion_Count
{
    internal class Program
    {

        private static void Main()
        {
            var a = Console.ReadLine()
                    .Split()
                    .Select(int.Parse)
                    .ToArray();
            int countInversion = mergeSort(a, 0, a.Length - 1);
            Console.WriteLine(countInversion);
        }

        public static int mergeSort(int[] a, int p, int r)
        {
            int countInversion = 0;
            if (p < r)
            {
                int q = (p + r) / 2;
                countInversion = mergeSort(a, p, q);
                countInversion += mergeSort(a, q + 1, r);
                countInversion += merge(a, p, q, r);
            }
            return countInversion;
        }

        public static int merge(int[] a, int p, int q, int r)
        {
            //p=0, q=1, r=3
            int countingInversion = 0;
            int n1 = q - p + 1;
            int n2 = r - q;
            int[] temp1 = new int[n1 + 1];
            int[] temp2 = new int[n2 + 1];
            for (int index0 = 0; index0 < n1; index0++) temp1[index0] = a[p + index0];
            for (int index0 = 0; index0 < n2; index0++) temp2[index0] = a[q + 1 + index0];

            temp1[n1] = Int32.MaxValue;
            temp2[n2] = Int32.MaxValue;
            int i = 0, j = 0;

            for (int k = p; k <= r; k++)
            {
                if (temp1[i] <= temp2[j])
                {
                    a[k] = temp1[i];
                    i++;
                }
                else
                {
                    a[k] = temp2[j];
                    j++;
                    countingInversion = countingInversion + (n1 - i);
                }
            }
            return countingInversion;
        }
    }
}