#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
//using mint = modint1000000007;
using mint = modint998244353;
template <typename T> bool chmax(T &u, const T z) { if (u < z) {u = z; return true;} else return false; }
template <typename T> bool chmin(T &u, const T z) { if (u > z) {u = z; return true;} else return false; }
#define ll long long
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
typedef pair<ll, int> P;
ll gcd(ll x, ll y) { return y ? gcd(y, x % y) : x; }
ll lcm(ll a, ll b){return a * b / gcd(a, b);}

int main(){
  int n;
  cin>>n;
  vector<ll>a(n),b(n-1);
  rep(i,n)cin>>a[i];
  rep(i,n-1){
    if(a[i]+a[i+1]==3)b[i]=3;
    else if(a[i]!=1&&a[i+1]!=1)b[i]=1;
    else b[i]=2;
  }
  //rep(i,n-1)cout<<b[i];
  ll ans=0;
  rep(i,n-1){
    ans+=b[i]*(n-i-1);
  }
  cout<<ans<<endl;
  return 0;
}