#include <bits/stdc++.h>
using namespace std;
const int MAXLEN = 5e5 + 5;
int t[MAXLEN], x, y, k, n, m, newa[MAXLEN];

struct Node {
	int id, val;
} a[MAXLEN];

void Change(int x, int k) {
	for (; x <= n; x += x & -(x)) {
		t[x] += k;
	}
	return ;
}

int query(int x) {
	int ret = 0;
	for (; x != 0; x -= x & -(x)) {
		ret += t[x];
	}
	return ret;
}

bool cmp(Node a, Node b) {
	return a.val < b.val;
}

void lisan() {
	sort(a + 1, a + 1 + n, cmp);
	for (int i = 1; i <= n; i++) {
		newa[a[i].id] = i;
	}
}

signed main() {
	scanf("%d", &n);
	for (int i = 1; i <= n; i++) {
		scanf("%d", &a[i].val);
		a[i].id = i;
	}
	lisan();
	long long ans = 0;
	for (int i = n; i >= 1; i--) {
		ans += query(newa[i] - 1);
		Change(newa[i], 1);
	}
	printf("%d", ans);
	return 0;
}