#include <bits/stdc++.h>
using namespace std;

// one-based numbering
template<class T> struct Fenwick {
    vector<T> bit; int N;
    Fenwick(int n) {
      N = n;
      bit.resize(n+1, 0);
    }
    void add(int a, T w) {
      for (int x = a; x <= N; x += x & -x) bit[x] += w;
    }
    T sum(int a) {
      T ret = 0;
      for (int x = a; x > 0; x -= x & -x) ret += bit[x];
      return ret;
    }
};

int main() {
	int n; cin >> n;
	Fenwick<long long> f(n);
	long long ans = 0;
	for (int i = 0; i < n; i++) {
		int k; cin >> k;
		ans += i - f.sum(k);
		f.add(k, 1);
	}
	cout << ans << endl;
}