/* created by chjshen, date: 2024-02-03 12:39 */
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <iostream>
using namespace std;
#define ls (fa << 1)
#define rs (fa << 1 | 1)
const int N = 1E5 + 5;
int n, a[N], b[N];
struct SegmentTree
{
    int l, r, sum;
} t[N << 2];
void build(int fa, int L, int R)
{
    t[fa].l = L, t[fa].r = R;
    t[fa].sum = 0;
    if (L == R) return;
    int mid = (L + R) >> 1;
    build(ls, L, mid);
    build(rs, mid + 1, R);
}
void update(int fa, int x)
{
    if (t[fa].l == t[fa].r)
    {
        t[fa].sum++;
        return;
    }
    int mid = (t[fa].l + t[fa].r) >> 1;
    if (x <= mid) update(ls, x);
    if (mid < x) update(rs, x);
    t[fa].sum = t[ls].sum + t[rs].sum;
}
long long query(int fa, int l, int r)
{
    if (l <= t[fa].l && t[fa].r <= r)
    {
        return t[fa].sum;
    }
    long long ans = 0;
    int mid = (t[fa].l + t[fa].r) >> 1;
    if (l <= mid) ans += query(ls, l, r);
    if (mid < r) ans += query(rs, l, r);
    return ans;
}
void handle(void)
{
    long long ans = 0;
    for (int i = n; i > 0; i--)
    {
        update(1, a[i]);
        ans += query(1, 1, a[i] - 1);
    }
    cout << ans << endl;
}
void initInput(void)
{
    ios::sync_with_stdio(0);
    cin >> n;
    for (int i = 1; i <= n; i++)
    {
        cin >> a[i];
        b[i] = a[i];
    }
    build(1, 1, n);  // 建立线段树
    // 离散化处理
    // 1. sort
    sort(b + 1, b + n + 1);
    // 2. 去重
    int m = unique(b + 1, b + n + 1) - b;
    // 3.重新对a数组赋值
    for (int i = 1; i <= n; i++) a[i] = lower_bound(b + 1, b + m + 1, a[i]) - b;
}
int main(void)
{
    initInput();
    handle();
    return 0;
}