#include <iostream>
#include <algorithm>

using namespace std;
const int N = 1e5 + 10;

long long ret = 0;
int a[N], f[N];

//归并排序
void merge_sort(int q[], int l, int r)
{
    if (l >= r) return;

    int mid = l + r >> 1;

    merge_sort(q, l, mid);
    merge_sort(q, mid + 1, r);
    //经过之后mid两边都是有序的

    int k = 0, i = l, j = mid + 1;
    while (i <= mid && j <= r)
        if (q[i] <= q[j]) f[k++] = q[i++];
        else f[k++] = q[j++], ret += mid - i + 1;
        //如果i处的数大于j处的，那么必然i~mid的也都大于j,所以与j匹配的就有mid - i + 1;
    while (i <= mid) f[k++] = q[i++];
    while (j <= r) f[k++] = q[j++];

    for (int i = l, j = 0; i <= r; i++, j++) q[i] = f[j];
}
int main()
{
    int n;
    cin >> n;
    for (int i = 1; i <= n; i++)
        cin >> a[i];

    merge_sort(a, 1, n);

    cout << ret;
    return 0;
}