#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <cassert>

#define debug_value(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << #x << "=" << x << endl;
#define debug(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << x << endl;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

using namespace std;
typedef long long ll;

ll tri(ll n){
    return (n*(n-1))/2;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << setprecision(10) << fixed;
    int n; cin >> n;
    vector<ll> a(n);
    for(int i = 0; i < n; i++) cin >> a[i];
    map<ll, ll> cnt;
    for(int x: a){
        if(cnt.count(x) == 0) cnt[x] = 1;
        else cnt[x]++;
    }
    ll m = n;
    ll ans = 0;
    if(cnt.count(1)){
        m -= cnt[1];
        ans += tri(cnt[1])*2;
        ll k = m;
        if(cnt.count(2)){
            ans += cnt[1]*cnt[2]*3;
            k -= cnt[2];
        }
        ans += cnt[1]*k*2;
    }
    ans += tri(m);
    cout << ans << endl;
}