#include <bits/stdc++.h>
#define For(i, a, b) for(int (i)=(int)(a); (i)<(int)(b); ++(i))
#define rFor(i, a, b) for(int (i)=(int)(a)-1; (i)>=(int)(b); --(i))
#define rep(i, n) For((i), 0, (n))
#define rrep(i, n) rFor((i), (n), 0)
#define fi first
#define se second
using namespace std;
typedef long long lint;
typedef unsigned long long ulint;
typedef pair<int, int> pii;
typedef pair<int, lint> pil;
typedef pair<lint, lint> pll;
template<class T>bool chmax(T &a, const T &b){if(a<b){a=b; return true;} return false;}
template<class T>bool chmin(T &a, const T &b){if(a>b){a=b; return true;} return false;}

constexpr lint mod = 1e9+7;
constexpr lint INF = mod*mod;
constexpr int MAX = 100010;

template<typename T> struct SegTree{
    using F=function<T(T, T)>;
    int sz=1;
    T et;
    F f, g;
    vector<T> node;

    SegTree(int sz_, T et_, F f_, F g_): et(et_), f(f_), g(g_){
        while(sz<sz_) sz<<=1;
        node.resize(sz<<1, et);
    }

    void update(int i, T x){
        i+=sz;
        node[i]=g(node[i], x);
        i>>=1;
        while(i){
            node[i]=f(node[i<<1], node[(i<<1)+1]);
            i>>=1;
        }
    }

    T query(int l, int r){
        T vl=et, vr=et;
        for(l+=sz, r+=sz; l<r; l>>=1, r>>=1){
            if(l&1) vl=f(vl, node[l++]);
            if(r&1) vr=f(node[--r], vr);
        }
        return f(vl, vr);
    }

    int search_left(int l, const T val, function<bool(T, T)> cmp, function<bool(T, T)> check){
        T sum = et;
        for(l+=sz; ; l>>=1){
            if(check(f(sum, node[l]), val)){
                while(l < sz){
                    if(check(f(sum, node[l<<1]), val)) l<<=1;
                    else{
                        sum = f(sum, node[l<<1]);
                        l = (l<<1) + 1;
                    }
                }
                return l-sz;
            }
            if(__builtin_popcount(l+1) == 1) return sz;
            if(l&1) sum = f(sum, node[l++]);
        }
    }

    int search_right(int r, const T val, function<bool(T, T)> cmp, function<bool(T, T)> check){
        T sum = et;
        for(r+=sz; ; r>>=1){
            if(check(f(sum, node[r]), val)){
                while(r < sz){
                    if(check(f(node[(r<<1)+1], sum), val)) r = (r<<1) + 1;
                    else{
                        sum = f(node[(r<<1)+1], sum);
                        r<<=1;
                    }
                }
                return r-sz;
            }
            if(__builtin_popcount(r) == 1) return -1;
            if(!(r&1)) sum = f(node[r--], sum);
        }
    }

    int lower_bound_left(int l, const T val, function<bool(T, T)> cmp=less<>()){
        auto check = [&cmp](auto a, auto b){return !cmp(a, b);};
        return search_left(l, val, cmp, check);
    }

    int upper_bound_left(int l, const T val, function<bool(T, T)> cmp=less<>()){
        auto check = [&cmp](auto a, auto b){return cmp(b, a);};
        return search_left(l, val, cmp, check);
    }

    int lower_bound_right(int l, const T val, function<bool(T, T)> cmp=greater<>()){
        auto check = [&cmp](auto a, auto b){return !cmp(b, a);};
        return search_right(l, val, cmp, check);
    }

    int upper_bound_right(int l, const T val, function<bool(T, T)> cmp=greater<>()){
        auto check = [&cmp](auto a, auto b){return cmp(a, b);};
        return search_right(l, val, cmp, check);
    }
};

int main(){
    int n;
    scanf("%d", &n);
    vector<int> p(n), pos(n);
    for(int &i: p){
        scanf("%d", &i);
    }
    rep(i, n) pos[i] = i;
    sort(pos.begin(), pos.end(), [&p](int a, int b){return p[a] > p[b];});

    SegTree<int> st(n, 0, plus<>(), plus<>());
    lint ans = 0;

    for(int i: pos){
        int a = st.upper_bound_right(i, 1);
        int b = st.lower_bound_right(i, 1);
        int c = min(n, st.lower_bound_left(i, 1));
        int d = min(n, st.upper_bound_left(i, 1));
        if(b >= 0) ans += (lint)p[i] * (b-a) * (c-i);
        if(c < n) ans += (lint)p[i] * (d-c) * (i-b);
        st.update(i, 1);
    }
    printf("%lld\n", ans);
}

Measured memory_bytes: 2048