инверсии OK

#include <iostream>
#include <cmath>
#include <vector>
#include <queue>
#include <algorithm>
#include <string>
#include <stack>
#include <set>
#include <map>
#define pii pair <int, int>
#define pb(x) push_back(x)
using namespace std;
using ll = long long;
using ld = long double;
using db = double;
void cv(vector <int> &v) {
    for (auto x : v) cout << x << ' ';
    cout << "\n";
}

void cvl(vector <ll> &v) {
    for (auto x : v) cout << x << ' ';
    cout << "\n";
}


void cvv(vector <vector <int> > &v) {
    for (auto x : v) cv(x);
    cout << "\n";
}

void cvb(vector <bool> v) {
    for (bool x : v) cout << x << ' ';
    cout << "\n";
}

void cvs(vector <string>  v) {
    for (auto a : v) {
        cout << a << "\n";
    }
}

void cvp(vector <pii> a) {
    for (auto p : a) {
        cout << p.first << ' ' << p.second << "\n";
    }
    cout << "\n";
}
ll ans = 0;
bool sh = 0;
vector <int> a;
void mrg(int l, int m, int r) {
    if (sh) {
        cout << "l r = " << l << ' ' << r << "\n";
    }
    int k = m;
    for (int i = l; i <= m ; ++i) {
        if (a[m + 1] >= a[i]) continue;
        if (sh) {
            cout << "i = " << i << "\n";
            cout << "a\n"; cv(a);
        }
        int L = m + 1, R =  r + 1, M;
        while (L + 1 < R) {
            M = (L + R) / 2;
            if (sh) {
                cout << "M = " << M << "\n";
            }
            if (a[M] >= a[i]) {
                R = M;
            } else {
                L = M;
            }
        }
        ans += (m - i + 1) * (L - k);
        if (sh) {
            cout << "ans += " << (m - i + 1) * (L - k) << "\n";
        }
        k = L;
    }

    vector <int> res;
    int A = l, B = m + 1;
    while (A <= m && B <= r) {
        if (a[A] < a[B]) {
            res.pb(a[A]);
            A++;
        } else {
            res.pb(a[B]);
            B++;
        }
    }
    while (A <= m) {
        res.pb(a[A]);
        A++;
    }
    while (B <= r) {
        res.pb(a[B]);
        B++;
    }
    for (int i = l; i <= r; ++i) {
        a[i] = res[i - l];
    }
}

void f(int l, int r) {
    if (l == r) {
        return;
    } else if (l + 1 == r) {
        if (a[l] > a[r]) {
            ans++;
            swap(a[l], a[r]);
        }
        return;
    }

    int m = (l + r) / 2;

    f(l, m);

    f(m + 1, r);
    mrg(l, m, r);
}

/*
5
179 4 3 2 1


9
179 4 3 2 1 11 100 0 2
*/

int main() {
    /*ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);*/
    int n; cin >> n;
    a.resize(n);
    for (int &i : a) cin >> i;

    f(0, n - 1);
    cout << ans;
}