using System;

public class Hello
{
    public static void Main()
    {
        var n = int.Parse(Console.ReadLine().Trim());
        var a = new int[n];
        for (int i = 0; i < n; i++) a[i] =  int.Parse(Console.ReadLine().Trim());
        var bit = new int[n + 1];
        var ans = 0;
        for (int i = 0; i < n; i++)
        {
            ans += i - getSum(a[i], bit);
            addix(a[i], 1, bit, n);
        }
        Console.WriteLine(ans);

    }
    public static int getSum(int i, int[] bit)
    {
        var s = 0;
        while (i > 0)
        {
            s += bit[i];
            i -= i & -i;
        }
        return s;
    }
    public static void addix(int i, int x, int[] bit, int n)
    {
        while (i <= n)
        {
            bit[i] += x;
            i += i & -i;
        }
    }
}