#include
#include
using namespace std;
typedef long long ll;
int tree[500000 * 4];
void update(int start, int end, int node, int index)
{
if (start > index || index > end)
return;
tree[node]++;
if (start == end)
return;
int mid = (start + end) / 2;
update(start, mid, node * 2, index);
update(mid + 1, end, node * 2 + 1, index);
}
ll query(int start, int end, int node, int left, int right)
{
if (start > right || end < left)
return 0;
if (left <= start && end <= right)
return tree[node];
int mid = (start + end) / 2;
return query(start, mid, node * 2, left, right) + query(mid + 1, end, node * 2 + 1, left, right);
}
int main()
{
cin.tie(0)->sync_with_stdio(false);
int N;
cin >> N;
pair arr[N];
for (int i = 0; i < N; i++)
{
int t;
cin >> t;
arr[i] = {t, i};
}
sort(arr, arr + N);
ll result = 0;
for (int i = 0; i < N; i++)
{
int index = arr[i].second;
update(0, N - 1, 1, index);
result += query(0, N - 1, 1, index + 1, N - 1);
}
cout << result;
return 0;
}