#include <iostream>
#include<vector>
#include<string>
#include<algorithm>
#include<iomanip>
#include<map>
#include<random>
#include<complex>
#include<math.h>
#include<functional>
#include<stack>
#include<queue>
#include<unordered_map>
#include<set>
#include<numeric>
#include <cassert>
using namespace std;
#define rep(i, n) for (int i = 0; i < (ll)(n); i++)
#define req(i,n) for(int i = 1;i <=  n; i++)
#define rrep(i,n) for(ll i = n-1;i >= 0;i--)
#define ALL(obj) begin(obj), end(obj)
#define RALL(a) rbegin(a),rend(a)
typedef long long ll;
typedef long double ld;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
const int inf = 0x3fffffff;
const ll INF = 1e18;
class BIT {
public:
	int n; vector<ll> a;
	BIT(int n) :n(n), a(n + 1, 0) {}
	void add(int i, ll x) {
		i++;
		if (i == 0)return;
		for (int j = i; j <= n; j += (j & -j)) a[j] += x;
	}ll sum(int i) {
		i++; ll sum = 0;
		if (i == 0)return sum;
		for (int j = i; j > 0; j -= (j & -j)) sum += a[j];
		return sum;
	}
};
int main() {
    int n; cin >> n; ll sum = 0,m;
    BIT bit(n + 1);
    rep(i, n) {
        cin >> m; sum += i - bit.sum(m);
		bit.add(m, 1);
    }cout << sum << endl;
}