#pragma GCC optimize("O3") //#pragma GCC target("avx2") //#pragma GCC optimize("unroll-loops") #include <bits/stdc++.h> using namespace std; typedef long long ll; typedef unsigned long long ull; typedef long double ld; typedef vector<int> vi; typedef vector<ll> vll; typedef vector<ld> vld; typedef pair<ll,ll> Pll; typedef pair<int,int> Pin; ll INF = 1e16; int inf = 1e9; #define ALL(x) (x).begin(), (x).end() #define FOR(i, m, n) for (ll i = (m); i < (n); ++i) #define REVFOR(i, m, n) for (ll i = (n - 1); i >= (m); --i) #define REP(i, n) FOR(i, 0, n) #define REVREP(i, n) REVFOR(i, 0, n) #define fi first #define se second #define pb push_back #define mp make_pair #define eb emplace_back #define bcnt __builtin_popcountll #ifdef LOCAL #include <prettyprint.hpp> #define debug(...) cerr << "[" << #__VA_ARGS__ << "]: ", d_err(__VA_ARGS__); #else #define debug(...) 83; #endif void d_err() { cerr << endl; } template <typename H, typename... T> void d_err(H h, T... t) { cerr << h << " "; d_err(t...); } template <typename T> void print(T x) { cout << x << "\n"; } template <typename T> void print(vector<T>& x) { int N = x.size(); REP(i, N) { if (i > 0) cout << " "; cout << x[i]; } cout << "\n"; } int main(){ cin.tie(0); ios_base::sync_with_stdio(false); cout << fixed << setprecision(20); int n; cin >> n; vll a(n); REP(i, n) cin >> a[i]; int c1 = 0, c2 = 0; REP(i, n) { if (a[i] == 1) c1++; else if (a[i] == 2) c2++; } ll ans = 0; ans += (c1 * (c1 - 1) / 2) * 2; ans += c1 * c2 * 3; print(ans); }