#include using namespace std; using VS = vector; using LL = long long; using VI = vector; using VVI = vector; using PII = pair; using PLL = pair; using VL = vector; using VVL = vector; #define ALL(a) begin((a)),end((a)) #define RALL(a) (a).rbegin(), (a).rend() #define PB push_back #define EB emplace_back #define MP make_pair #define SZ(a) int((a).size()) #define SORT(c) sort(ALL((c))) #define RSORT(c) sort(RALL((c))) #define UNIQ(c) (c).erase(unique(ALL((c))), end((c))) #define FOR(i, s, e) for (int(i) = (s); (i) < (e); (i)++) #define FORR(i, s, e) for (int(i) = (s); (i) > (e); (i)--) #define debug(x) cerr << #x << ": " << x << endl const int INF = 1e9; const LL LINF = 1e16; const LL MOD = 1000000007; const double PI = acos(-1.0); int DX[8] = { 0, 0, 1, -1, 1, 1, -1, -1 }; int DY[8] = { 1, -1, 0, 0, 1, -1, 1, -1 }; /* ----- 2018/04/26 Problem: yukicoder 121 / Link: http://yukicoder.me/problems/no/121 ----- */ /* ------問題------ -----問題ここまで----- */ /* -----解説等----- ----解説ここまで---- */ template struct BIT { // 1-index int N; int nn; vector data; BIT(int n) { N = n + 1; data = vector(n + 1, 0); nn = 1; while (nn * 2 <= N)nn *= 2; } void add(int i, type w) { // a[i] += w for (int x = i; x <= N; x += x & -x) { data[x] += w; } } type sum(int i) { // iまでの和 [1,i] type ret = 0; for (int x = i; x > 0; x -= x & -x) { ret += data[x]; } return ret; } // [l, r] type sum(int l, int r) { if (l > r) return 0; return sum(r) - sum(l - 1); } }; LL N; LL ans = 0LL; int main() { cin.tie(0); ios_base::sync_with_stdio(false); cin >> N; VI a(N); FOR(i, 0, N) { cin >> a[i]; } VI b = a; SORT(b); UNIQ(b); FOR(i, 0, N) { a[i] = lower_bound(ALL(b), a[i]) - b.begin() + 1; } BITbitL(N), bitR(N); VL cntL(N, 0), cntR(N, 0); FOR(i, 0, N) { bitR.add(a[i], 1); cntR[a[i]]++; } FOR(i, 0, N) { bitR.add(a[i], -1); ans += bitL.sum(a[i] - 1)*bitR.sum(a[i] - 1); ans += bitL.sum(a[i] + 1, N)*bitR.sum(a[i] + 1, N); bitL.add(a[i], 1); } LL sum = 0; FOR(i, 0, N) { // a==cみたいなのを除く ans -= sum - cntL[a[i]] * cntR[a[i]]; LL before = cntL[a[i]] * cntR[a[i]]; cntL[a[i]]++; cntR[a[i]]--; LL diff = before - cntL[a[i]] * cntR[a[i]]; sum -= diff; } cout << ans << "\n"; return 0; }