#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

vector<int> v;

long long mergeAndCount(int l, int m, int r) {

    long long cnt = 0;
    int i = l, j = m + 1, y = l;
    auto b = v;

    while (m - i >= 0 && r - j >= 0) {
        if (v[i] < v[j]) {
            b[y] = v[i];
            i++;
        } else {
            cnt += m - i + 1;
            b[y] = v[j];
            j++;
        }
        y++;
    }
    if (i > m) {
        for (int k = j; k <= r; k++) {
            b[y] = v[k];
            y++;
        }
    } else {
        for (int k = i; k <= m; k++) {
            b[y] = v[k];
            y++;
        }
    }
    v = b;
    return cnt;
}


long long countInversions(int l, int r) {
    if (r - l < 1) {
        return 0;
    }
    int m = (r + l) / 2;

    auto res = countInversions(l, m);
    res += countInversions(m + 1, r);
    res += mergeAndCount(l, m, r);
    return res;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie();
    cout.tie();

    int n, x;
    cin >> n;


    for (int i = 0; i < n; i++) {
        cin >> x;
        v.push_back(x);
    }
    cout << countInversions(0, v.size() - 1);
}