import java.util.*;
class Main {
    static long cnt;
    public static void main(String[] args) {
        cnt = 0;
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] arr = new int[n];

        for (int i = 0; i < n; i++)
            arr[i] = Integer.parseInt(sc.next());

        divide(arr);
        System.out.println(cnt);
    }


    public static int[] divide(int[] arr) {
        if (arr.length <= 1)
            return arr;

        int mid = arr.length / 2;
        int[] left = new int[mid];
        int[] right = new int[arr.length - mid];
        int l = 0, r = 0;
        for (int i = 0; i < arr.length; i++) {
            if (i < mid)
                left[l++] = arr[i];
            else
                right[r++] = arr[i];
        }
        left = divide(left);
        right = divide(right);
        int[] sorted = merge(left, right);
        return sorted;
    }

    /**
     * arr1 - left arr, arr2 - right arr
     */
    public static int[] merge(int[] arr1, int[] arr2) {
        int n = arr1.length, m = arr2.length; 
        int[] newArr = new int[n + m];

        int i = 0, j = 0;
        int idx = 0;
        while (i < n && j < m) {
            if (arr1[i] <= arr2[j])
                newArr[idx++] = arr1[i++];
            else {
                cnt += (n - i);
                newArr[idx++] = arr2[j++];
            }
        }

        for (; i < n; i++)
            newArr[idx++] = arr1[i];

        for (; j < m; j++)
            newArr[idx++] = arr2[j];
        return newArr;
    }
}