#include <iostream>

 #include <cstdio>

 #include <algorithm>

 using namespace std;

 const int MAXN = ;

 int n, a[MAXN], tmp[MAXN];

 long long cnt = ;

 void mergeSort(int * a, int left, int right, int * tmp)

 {

     if (left >= right)

         return;

     int mid = (left + right) / ;

     mergeSort(a, left, mid, tmp);

     mergeSort(a, mid + , right, tmp);

     int x = left;

     int y = mid + ;

     int start = left;

     while (x <= mid && y <= right)

     {

         if (a[x] < a[y])

         {

             tmp[start++] = a[x++];

         }

         else

         {

             int pos = upper_bound(a + x, a + mid + ,  * a[y]) - a;

             cnt += mid - pos + ;

             tmp[start++] = a[y++];

         }

     }

     while(x <= mid)

     {

         tmp[start++] = a[x++];

     }

     while(y <= right)

     {

         tmp[start++] = a[y++];

     }

     for (int i = left; i <= right; i++)

     {

         a[i] = tmp[i];

     }

 }

 int main()

 {

     scanf("%d", &n);

     for (int i = ; i < n; i++)

     {

         scanf("%d", &a[i]);

     }

     mergeSort(a, , n - , tmp);

     cout << cnt << endl;

     return ;

 }