#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


long _mergeSort(int arr[], int temp[], int left, int right);
long merge(int arr[], int temp[], int left, int mid, int right);

long mergeSort(int arr[], long size)
{
    int * array= new int [size];
    return _mergeSort(arr, array, 0, size - 1);
    delete[] array;
}

long _mergeSort(int arr[], int temp[], int start, int end)
{
    long  numberOfInversions = 0;
    if (start < end) {

        int mid = (end + start) / 2;


        numberOfInversions = _mergeSort(arr, temp, start, mid);
        numberOfInversions += _mergeSort(arr, temp, mid + 1, end);


        numberOfInversions += merge(arr, temp, start, mid + 1, end);
    }
    return numberOfInversions;
}

long merge(int arr[], int temp[], int start, int mid, int end)
{

    long numberOfInversions = 0;

    int left = start;
    int right = mid;
    int beginOfArray = start;

    while ((left <= mid - 1) && (right <= end)) {
        if (arr[left] <= arr[right]) {
            temp[beginOfArray++] = arr[left++];
        }
        else {
            temp[beginOfArray++] = arr[right++];

            numberOfInversions = numberOfInversions + (mid - left);
        }
    }


    while (left <= mid - 1)
        temp[beginOfArray++] = arr[left++];

    while (right <= end)
        temp[beginOfArray++] = arr[right++];

    for (left = start; left <= end; left++)
        arr[left] = temp[left];

    return numberOfInversions;
}

int main()
{
    long numberOfBuildings = 0;
    cin >> numberOfBuildings;
    long y = 0;

    int * buildingsHeight = new int[numberOfBuildings];

    for (int i = 0; i < numberOfBuildings; i++) {
        cin >> buildingsHeight[i];
    }
    y= mergeSort(buildingsHeight, numberOfBuildings);
    cout<<y;

    delete[] buildingsHeight;
}