#pragma GCC target("avx2") #pragma GCC optimize("Ofast") #pragma GCC optimize("unroll-loops") #include <bits/stdc++.h> //#include <atcoder/all> using namespace std; //using namespace atcoder; #define DEBUG #ifdef DEBUG template <class T, class U> ostream &operator<<(ostream &os, const pair<T, U> &p) { os << '(' << p.first << ',' << p.second << ')'; return os; } template <class T> ostream &operator<<(ostream &os, const vector<T> &v) { os << '{'; for(int i = 0; i < (int)v.size(); i++) { if(i) { os << ','; } os << v[i]; } os << '}'; return os; } void debugg() { cerr << endl; } template <class T, class... Args> void debugg(const T &x, const Args &... args) { cerr << " " << x; debugg(args...); } #define debug(...) \ cerr << __LINE__ << " [" << #__VA_ARGS__ << "]: ", debugg(__VA_ARGS__) #define dump(x) cerr << __LINE__ << " " << #x << " = " << (x) << endl #else #define debug(...) (void(0)) #define dump(x) (void(0)) #endif using namespace std; typedef long long ll; typedef vector<ll> vl; typedef vector<vector<ll>> vvl; typedef vector<char> vc; typedef vector<string> vs; typedef vector<bool> vb; typedef vector<double> vd; typedef pair<ll,ll> P; typedef pair<int,int> pii; typedef vector<P> vpl; typedef tuple<ll,ll,ll> tapu; #define rep(i,n) for(int i=0; i<(n); i++) #define REP(i,a,b) for(int i=(a); i<(b); i++) #define all(x) (x).begin(), (x).end() #define rall(x) (x).rbegin(), (x).rend() const int inf = (1<<30) - 1; const ll linf = 1LL<<61; const int MAX = 510000; int dy[8] = {0,1,0,-1,1,-1,-1,1}; int dx[8] = {-1,0,1,0,1,-1,1,-1}; const double pi = acos(-1); const double eps = 1e-8; template<typename T1,typename T2> inline bool chmin(T1 &a,T2 b){ if(a>b){ a = b; return true; } else return false; } template<typename T1,typename T2> inline bool chmax(T1 &a,T2 b){ if(a<=b){ a = b; return true; } else return false; } template<typename T> inline void print(T &a){ int sz = a.size(); for(auto itr = a.begin(); itr != a.end(); itr++){ cout << *itr; sz--; if(sz) cout << " "; } cout << "\n"; } template<typename T1,typename T2> inline void print2(T1 a, T2 b){ cout << a << " " << b << "\n"; } template<typename T1,typename T2,typename T3> inline void print3(T1 a, T2 b, T3 c){ cout << a << " " << b << " " << c << "\n"; } void mark() {cout << "#" << "\n";} ll pcount(ll x) {return __builtin_popcountll(x);} //const int mod = 1e9 + 7; const int mod = 998244353; int main(){ int n; cin >> n; vl a(n); rep(i,n) cin >> a[i]; vl cnt(4,0); rep(i,n) cnt[min(a[i],3LL)]++; ll ans = 0; ans += cnt[1] * (cnt[1] - 1); ans += cnt[1] * cnt[2] * 3; ans += cnt[1] * cnt[3] * 2; ans += cnt[2] * (cnt[2] - 1) / 2; ans += cnt[2] * cnt[3]; ans += cnt[3] * (cnt[3] - 1) / 2; cout << ans << endl; }