#include<bits/stdc++.h>
using namespace std;
#define ll long long
int main(){
    ll n;
    cin>>n;
    ll x=0,y=0;
    for(ll i=0;i<n;i++){
        int a;
        cin>>a;
        if(a==1) x++;
        else if(a==2) y++;
    }
    ll ans=0;
    ans+=3*x*y;
    ans+=x*(x-1);
    ans+=(n*(n-1)/2-x*y-x*(x-1)/2);
    cout<<ans<<endl;
}