BALE11

#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e5 + 10;
array<int, MAXN> v, bit;

void update(int id, int val)
{
    while (id < MAXN)
    {
        bit[id] += val;
        id += id&-id;
    }
}

int query(int id)
{
    int resp = 0;
    while (id > 0)
    {
        resp += bit[id];
        id -= id&-id;
    }
    return resp;
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int N; cin >> N;
    for (int i = 0; i < N; i++) cin >> v[i];

    long long resp = 0;
    for (int i = N-1; i >= 0; i--)
    {
        resp += query(v[i]-1);
        update(v[i], 1);
    }
    cout << resp << '\n';
}