#include <bits/stdc++.h> using namespace std ; typedef long long ll ; #define rep(i,n) for(int i = 0 ; i < n ; i++) #define rrep(i,a,b) for(int i = a ; i < b ; i++) int n ; int main(){ cin >> n ; ll one = 0 , two = 0 , other = 0 ; for(int i = 0 ; i < n ; i++){ int a ; cin >> a ; if(a == 1) one++ ; if(a == 2) two++ ; } cout << one * (one - 1) + 3 * one * two + (n - one) * (n - one - 1) / 2 << endl ; }