#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using ll = long long;

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
    int n;
    cin >> n;
    vector<int> a(n);
    for(auto &&v : a) cin >> v;
    auto ca = a;
    sort(ca.begin(), ca.end());
    ca.erase(unique(ca.begin(), ca.end()), ca.end());
    ll ans = 0;
    int m = ca.size();
    atcoder::fenwick_tree<int> fw(m);
    for(auto &&v : a){
        v = lower_bound(ca.begin(), ca.end(), v) - ca.begin();
        ans += fw.sum(v + 1, m);
        fw.add(v, 1);
    }
    cout << ans << '\n';
}