// Programmer: Shadow1
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
using str = string; // yay python!
#define i64 int64_t
#define watch(x) cerr << (#x) << " = " << (x) << '\n';
#define output_vector(v) for(auto &x : v){cout << x << " ";}cout << '\n';
#define vt vector
#define st stack
#define pq priority_queue
#define pb push_back
#define eb emplace_back
#define pii pair<int,int>
#define umap unordered_map
#define uset unordered_set
#define fir first
#define sec second
#define sz(x) int(x.size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
// T: O(n log n)
// M : O(n + k log n)
class FenwickTree {
private:
vector<int64_t> ft;
public:
FenwickTree(int m) { // Create empty Fenwick Tree
ft.assign(m+1,0);
}
int LSOne(int x) { // Return Least significant 1-bit of x
return ((x) & (-x));
}
void build(const vector<int64_t> &f) { // Build the fenwick tree array from the frequency array
int m = sz(f) - 1;
ft.assign(m+1,0);
for(int i=1; i<=m; ++i) {
ft[i] += f[i];
if(i + LSOne(i) <= m)
ft[i+LSOne(i)] += ft[i];
}
}
FenwickTree(int m, const vector<int64_t> &s) { // Convert the array to a frequency array with m integer keys
vector<int64_t> f(m+1,0); // i.e. the array's maximum value must be m
for(int i=0; i<sz(s); ++i)
++f[s[i]];
}
int64_t rsq(int i, int j) { // i <= j // O(log m)
int64_t sum = 0;
while(j > 0) {
sum += ft[j];
j -= LSOne(j);
}
--i;
while(i > 0) {
sum -= ft[i];
i -= LSOne(i);
}
return sum;
}
void update(int i, int64_t v) {
for(; i<sz(ft); i+=LSOne(i)) // O(log m)
ft[i] += v;
}
};
void solve() {
int n;
cin >> n;
vector<int64_t> h(n), cnt(n+1), p(n+1); // cnt[i] is the number of ith smallest elements.
set<int64_t> s;
map<int64_t, int> rank;
for(int i=0; i<n; ++i) { // O(n log n)
cin >> h[i];
s.insert(h[i]);
}
int k = 1;
for(auto &S : s) { // Worse case O(n log n)
rank[S] = k; // S is the kth smallest element
++k;
}
--k;
assert(k <= n);
for(auto &H : h)
cnt[rank[H]]++;
p[1] = cnt[1];
for(int i=2; i<=k; ++i)
p[i] = p[i-1] + cnt[i];
// Algorithm starts:
FenwickTree ft(k); // ft[i] will contain the number of ith smallest elements
int64_t ans = 0;
ft.update(rank[h[0]],1);
for(int i=1; i<n-1; ++i) {
int64_t x = ft.rsq(1,rank[h[i]]-1); // O(log n)
int64_t y = p[rank[h[i]]-1];
ans += (x * (y - x));
ft.update(rank[h[i]],1); // update
}
cout << ans << '\n';
}
int main() {
// freopen("output.txt", "w", stdout);
// freopen("input.txt", "r", stdin);
ios::sync_with_stdio(false);
cin.tie(NULL);
solve();
return 0;
}
/* CHECK :
1. COMPARATOR FUNCTION MUST RETURN FALSE WHEN ARGUMENTS ARE EQUAL!!!
2. Overflow! Typecase int64_t on operations if varaibles are int
3. Check array bounds!!!
4. Check array indexing!!!
5. Edge cases. (N==1)!!!
*/
