#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;

#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define all(x) begin (x), end(x)
#define sz(x) (int) (x).size()
#define rep(i,a,b) for (int i = (a); i < (b); i++)

mt19937 rng(random_device{}());

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    
    int n;
    cin >> n;
    vi a(n+1);
    rep(i,1,n+1) cin >> a[i];
    sort(a.begin(), a.end());
    int mexSum = 0;
    auto it_1 = upper_bound(a.begin()+1, a.end(), 1);
    it_1--;
    int qtd_1 = it_1 - a.begin();
    auto it_2 = upper_bound(a.begin()+1, a.end(), 2);
    it_2--;
    int qtd_2 = it_2 - it_1;
    int remainder = n - qtd_1 - qtd_2;
    int comb = qtd_1 * qtd_2;
    mexSum = 3*comb;
    mexSum += 2 * qtd_1/2 * (qtd_1-1);
    mexSum += (qtd_2 * (qtd_2-1))/2;
    mexSum += remainder;
    cout << mexSum;
}