#include <bits/stdc++.h>
using namespace std;

#define INF_LL (int64)1e18
#define INF (int32)1e9
#define REP(i, n) for(int64 i = 0;i < (n);i++)
#define FOR(i, a, b) for(int64 i = (a);i < (b);i++)
#define all(x) x.begin(),x.end()
#define fs first
#define sc second

using int32 = int_fast32_t;
using uint32 = uint_fast32_t;
using int64 = int_fast64_t;
using uint64 = uint_fast64_t;
using PII = pair<int32, int32>;
using PLL = pair<int64, int64>;

const double eps = 1e-10;

template<typename A, typename B>inline void chmin(A &a, B b){if(a > b) a = b;}
template<typename A, typename B>inline void chmax(A &a, B b){if(a < b) a = b;}

template<typename T>
vector<T> make_v(size_t a){return vector<T>(a);}

template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts){
  return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}

template<typename T,typename U,typename... V>
typename enable_if<is_same<T, U>::value!=0>::type
fill_v(U &u,const V... v){u=U(v...);}

template<typename T,typename U,typename... V>
typename enable_if<is_same<T, U>::value==0>::type
fill_v(U &u,const V... v){
  for(auto &e:u) fill_v<T>(e,v...);
}

template<class ValueMonoid, template<class...> class Container=::std::vector>
class SegTree{
public:
    using value_structure = ValueMonoid;
    using value_type = typename value_structure::value_type;
    using const_reference = const value_type &;
    using container_type = Container<value_type>;
    using size_type = typename container_type::size_type;

private:
    ::std::vector<value_type> tree;
    size_type size_;

    static size_type getsize(const size_type x){
        size_type ret = 1;
        while(ret < x)
            ret <<= 1;
        return ret;
    }

    inline value_type calc(const value_type a, const value_type b){
        return value_structure::operation(a, b);
    }

    inline void calc_node(const size_type index){
        if(tree.size() <= (index << 1 | 1)) return;
        tree[index] = value_structure::operation(tree[index<<1], tree[index<<1 | 1]);
    }
public:
    SegTree() : size_(0), tree(){}
    SegTree(const size_type size)
            : size_(size), tree(size << 1, value_structure::identity()){}
    template<class InputIterator>
    SegTree(InputIterator first, InputIterator last)
            : size_(::std::distance(first, last)){
        tree = container_type(size_, value_structure::identity());
        tree.insert(tree.end(), first, last);
        for(size_type i = size_;i > 0;i--){
            calc_node(i);
        }
    }

    size_type size() const { return size_; }
    const_reference operator[](const size_type k) const {
        assert(k < size_);
        return tree[k+size_];
    }

    value_type query(size_type l, size_type r){
        assert(l <= r);
        assert(0 <= l && l < size_);
        assert(0 <= r && r <= size_);
        value_type retl = value_structure::identity(), retr = value_structure::identity();
        for(l += size_, r += size_; l < r ; l >>= 1, r >>= 1){
            if(l&1) retl = calc(retl, tree[l++]);
            if(r&1) retr = calc(tree[--r], retr);
        }
        return calc(retl, retr);
    }

    template<class F>
    void update(size_type index, const F& f){
        assert(0 <= index && index < size());
        index += size_;
        tree[index] = f(::std::move(tree[index]));
        while(index >>= 1)
            calc_node(index);
    }

    /*
    template<class F>
    size_type search(const F& f) const { // [0, result) is True and [0, result-1) is not.
        if(f(value_structure::identity()))
            return 0;
        if(!f(tree[1]))
            return size_+1;
        value_type acc = value_structure::identity();
        size_type i = 1;
        while(i <
    }
    */
};

template<class ValueMonoid, int HEIGHT = 20> // HEIGHT is log size
class SparseTable {
private:
    using value_structure = ValueMonoid;
    using value_type = typename value_structure::value_type;
    using size_type = std::uint32_t;

    size_type size_;
    std::array<std::vector<value_type>, HEIGHT> table;
public:
    SparseTable() : size_(0) {}
    SparseTable(const std::vector<value_type>& v) : size_(v.size()) {
        table[0] = v;
        for (size_type i = 1, w = 1; i < HEIGHT; i++, w *= 2) {
            table[i].resize(size_, value_structure::identity());
            for (size_type j = 0; j < size_; j++) {
                if (j + w < size_) table[i][j] = value_structure::operation(table[i-1][j], table[i-1][j+w]);
                else table[i][j] = table[i-1][j];
            }
        }
    }

    static inline size_type log2(size_type x) {
        if (x == 0) return 0;
        return size_type(31) ^ __builtin_clz(x);
    }

    value_type query(size_type l, size_type r) {
        if (r <= l) return value_structure::identity();
        size_type k = log2(r - l);
        return value_structure::operation(table[k][l], table[k][r-(size_type(1) << k)]);
    }
};

class v_monoid {
public:
    using value_type = int64;
    static value_type identity() { return 0; }
    static value_type operation (const value_type& a, const value_type& b) {
        return max(a, b);
    }
};

int main(void) {
    int64 N;
    cin >> N;
    vector<int64> P(N);
    REP(i, N) cin >> P[i];
    SparseTable<v_monoid> st(P);

    int64 res = 0;
    REP(i, N) {
        int64 l = -1, r = i, m;
        auto lbin = [&](int64 l, int64 r) {
            int64 fr = r;
            while (r - l > 1) {
                m = (l + r + 1) >> 1;
                if (st.query(m, fr) < P[i]) {
                    r = m;
                } else {
                    l = m;
                }
            }
            return r;
        };
        auto rbin = [&](int64 l, int64 r) {
            int64 fl = l;
            while (r - l > 1) {
                m = (l + r) >> 1;
                if (st.query(fl + 1, m) < P[i]) {
                    l = m;
                } else {
                    r = m;
                }
            }
            return l;
        };
        int64 ll = lbin(-1, i), rr = rbin(i, N+1);
        int64 ll2 = lbin(-1, ll-1), rr2 = rbin(rr, N+1);
        chmax(ll, (int64)0);
        chmax(ll2, (int64)0);
        if (ll != ll2) {
            res += (ll - ll2) * (rr - i) * P[i];
        }
        if (rr != rr2) {
            res += (i - ll + 1) * (rr2 - rr) * P[i];
        }
    }
    cout << res << endl;
}


Measured memory_bytes: 16768