#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()
{
    cin.tie(0)->sync_with_stdio(0);

    int n;
    cin >> n;
    ll c1 = 0, c2 = 0;
    rep(i,0,n){
        int a;
        cin >> a;
        if(a == 1) c1++;
        else if(a == 2) c2++;
    }

    ll total = (ll)n*(n-1)/2;
    ll ans = total + c1*(n-c1) + c1*(c1-1)/2 + c1*c2;
    cout << ans << endl;

    return 0;
}