#include <bits/stdc++.h>
#include <unistd.h>

using namespace std;

#define DEBUG(x) cerr<<#x<<": "<<x<<endl;
#define DEBUG_VEC(v) cerr<<#v<<":";for(int i=0;i<v.size();i++) cerr<<" "<<v[i]; cerr<<endl
#define DEBUG_MAT(v) cerr<<#v<<endl;for(int i=0;i<v.size();i++){for(int j=0;j<v[i].size();j++) {cerr<<v[i][j]<<" ";}cerr<<endl;}


typedef long long ll;

#define vi vector<int>
#define vl vector<ll>
#define vii vector< vector<int> >
#define vll vector< vector<ll> >
#define vs vector<string>
#define pii pair<int,int>
#define pis pair<int,string>
#define psi pair<string,int>
#define pll pair<ll,ll>
template<class S, class T> pair<S, T> operator+(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first + t.first, s.second + t.second); }
template<class S, class T> pair<S, T> operator-(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first - t.first, s.second - t.second); }
template<class S, class T> ostream& operator<<(ostream& os, pair<S, T> p) { os << "(" << p.first << ", " << p.second << ")"; return os; }
#define X first
#define Y second
#define rep(i,n) for(int i=0;i<(n);i++)
#define rep1(i,n) for(int i=1;i<=(n);i++)
#define rrep(i,n) for(int i=(n)-1;i>=0;i--)
#define rrep1(i,n) for(int i=(n);i>0;i--)
#define REP(i,a,b) for(int i=a;i<b;i++)
#define in(x, a, b) (a <= x && x < b)
#define all(c) c.begin(),c.end()
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a = b; return 1; } return 0; }
#define UNIQUE(v) v.erase(std::unique(v.begin(), v.end()), v.end());
const ll inf = 1000000001;
const ll INF = (ll)1e18 + 1;
const ll MOD = 1000000007;
//const ll MOD = 998244353;
const double pi = 3.14159265358979323846;
#define Sp(p) cout<<setprecision(15)<< fixed<<p<<endl;
int dx[4] = { -1,0, 1,0 }, dy[4] = { 0,1,0,-1 };
int dx2[8] = { 1,1,0,-1,-1,-1,0,1 }, dy2[8] = { 0,1,1,1,0,-1,-1,-1 };
#define fio() cin.tie(0); ios::sync_with_stdio(false);
// #define mp make_pair
//#define endl '\n'


int main() {
  int n;
  cin >> n;
  vi p(n + 2, inf);
  vi p2i(n + 2);
  rep1 (i, n) {
    cin >> p[i];
    p2i[p[i]] = i;
  }
  vii left(n + 2, vi(2, 0));
  vii right(n + 2, vi(2, n + 1));

  set<int> st;
  rrep1 (i, n) {
    int idx = p2i[i];
    auto itr = st.lower_bound(idx);
    rep (j, 2) {
      if (itr == st.end()) break;
      right[idx][j] = *itr;
      itr++;
    }
    itr = st.lower_bound(idx);
    rep (j, 2) {
      if (itr == st.begin()) break;
      itr--;
      left[idx][j] = *itr;
    }
    st.insert(idx);
  }
  //DEBUG_MAT(left);
  //DEBUG_MAT(right);

  /*
  left = vii(n + 2, vi(2, 0));
  right = vii(n + 2, vi(2, n + 1));
  rep1 (i, n) {
    int cnt = 0;
    for (int j = i + 1; j <= n + 1; j++) {
      if (p[i] < p[j]) {
        right[i][cnt] = j;
        cnt++;
        if (cnt == 2) break;
      }
    }
    cnt = 0;
    for (int j = i - 1; j >= 0; j--) {
      if (p[i] < p[j]) {
        left[i][cnt] = j;
        cnt++;
        if (cnt == 2) break;
      }
    }
  }
  //*/

  //DEBUG_MAT(left);
  //DEBUG_MAT(right);
  
  ll ans = 0;
  ll cnt = 0;
  //DEBUG_MAT(left);
  //DEBUG_MAT(right);
  rep1 (i, n) {
    cnt += (ll)(left[i][0] - left[i][1]) * (right[i][0] - i);
    cnt += (ll)(right[i][1] - right[i][0]) * (i - left[i][0]);
    ans += (ll)(left[i][0] - left[i][1]) * (right[i][0] - i) * p[i];
    ans += (ll)(right[i][1] - right[i][0]) * (i - left[i][0]) * p[i];
  }
  // DEBUG(cnt);
  cout << ans << endl;
}


Measured memory_bytes: 16640