#include <iostream>

using namespace std;

typedef long long ll;
const int N = 100010;
int n, q[N], temp[N];

ll megerSort(int l, int r) {
    if (l >= r) return 0;

    int mid = l + r >> 1;

    ll ret = megerSort(l, mid) + megerSort(mid + 1, r);

    int i = l, j = mid + 1, k = 0;

    while (i <= mid && j <= r) {
        if (q[i] <= q[j]) temp[k++] = q[i++];
        else {
            ret += mid - i + 1;
            temp[k++] = q[j++];
        }
    }

    while (i <= mid) temp[k++] = q[i++];
    while (j <= r) temp[k++] = q[j++];

    for (i = l, j = 0; i <= r; ++i, ++j) q[i] = temp[j];

    return ret;//不传给上一层的话，就断掉了，所以要return
}

int main() {
    cin >> n;

    for (int i = 0; i < n; ++i)
        cin >> q[i];

    cout << megerSort(0, n - 1) << endl;

    return 0;
}