#include <bits/stdc++.h>
// clang-format off
#pragma GCC diagnostic ignored "-Wsign-compare"
#pragma GCC diagnostic ignored "-Wsign-conversion"
#define NDEBUG
#define SHOW(...) static_cast<void>(0)
//!===========================================================!//
//!  dP     dP                          dP                    !//
//!  88     88                          88                    !//
//!  88aaaaa88a .d8888b. .d8888b. .d888b88 .d8888b. 88d888b.  !//
//!  88     88  88ooood8 88'  '88 88'  '88 88ooood8 88'  '88  !//
//!  88     88  88.  ... 88.  .88 88.  .88 88.  ... 88        !//
//!  dP     dP  '88888P' '88888P8 '88888P8 '88888P' dP        !//
//!===========================================================!//
template <typename T>
T read()
{
    T v;
    return std::cin >> v, v;
}
template <typename T>
std::vector<T> readVec(const std::size_t l)
{
    std::vector<T> v(l);
    for (auto& e : v) { std::cin >> e; }
    return v;
}
using ld = long double;
using uint = unsigned int;
using ll = long long;
using ull = unsigned long long;
constexpr unsigned int MOD = 1000000007;
template <typename T>
constexpr T INF = std::numeric_limits<T>::max() / 4;
template <typename F>
constexpr F PI = static_cast<F>(3.1415926535897932385);
std::mt19937 mt{std::random_device{}()};
template <typename T>
bool chmin(T& a, const T& b) { return (a > b ? a = b, true : false); }
template <typename T>
bool chmax(T& a, const T& b) { return (a < b ? a = b, true : false); }
template <typename T>
std::vector<T> Vec(const std::size_t n, T v) { return std::vector<T>(n, v); }
template <class... Args>
auto Vec(const std::size_t n, Args... args) { return std::vector<decltype(Vec(args...))>(n, Vec(args...)); }
template <typename T>
constexpr T popCount(const T u)
{
#ifdef __has_builtin
    return u == 0 ? T(0) : (T)__builtin_popcountll(u);
#else
    unsigned long long v = static_cast<unsigned long long>(u);
    return v = (v & 0x5555555555555555ULL) + (v >> 1 & 0x5555555555555555ULL), v = (v & 0x3333333333333333ULL) + (v >> 2 & 0x3333333333333333ULL), v = (v + (v >> 4)) & 0x0F0F0F0F0F0F0F0FULL, static_cast<T>(v * 0x0101010101010101ULL >> 56 & 0x7f);
#endif
}
template <typename T>
constexpr T log2p1(const T u)
{
#ifdef __has_builtin
    return u == 0 ? T(0) : T(64 - __builtin_clzll(u));
#else
    unsigned long long v = static_cast<unsigned long long>(u);
    return v = static_cast<unsigned long long>(v), v |= (v >> 1), v |= (v >> 2), v |= (v >> 4), v |= (v >> 8), v |= (v >> 16), v |= (v >> 32), popCount(v);
#endif
}
template <typename T>
constexpr T clog(const T v) { return v == 0 ? T(0) : log2p1(v - 1); }
template <typename T>
constexpr T msbp1(const T v) { return log2p1(v); }
template <typename T>
constexpr T lsbp1(const T v)
{
#ifdef __has_builtin
    return __builtin_ffsll(v);
#else
    return v == 0 ? T(0) : popCount((v & (-v)) - T(1)) + T(1);
#endif
}
template <typename T>
constexpr bool ispow2(const T v) { return popCount(v) == 1; }
template <typename T>
constexpr T ceil2(const T v) { return v == 0 ? T(1) : T(1) << log2p1(v - 1); }
template <typename T>
constexpr T floor2(const T v) { return v == 0 ? T(0) : T(1) << (log2p1(v) - 1); }
//!================================================================!//
//!   88888888b                              oo          dP        !//
//!   88                                                 88        !//
//!  a88aaaa    .d8888b. 88d888b. dP  dP  dP dP .d8888b. 88  .dP   !//
//!   88        88ooood8 88'  '88 88  88  88 88 88'  '"" 88888"    !//
//!   88        88.  ... 88    88 88.88b.88' 88 88.  ... 88  '8b.  !//
//!   dP        '88888P' dP    dP 8888P Y8P  dP '88888P' dP   'YP  !//
//!================================================================!//
template <typename T = ll>
class Fenwick
{
public:
    Fenwick(const std::size_t N, const T initial = T{}) : size(N), cap(ceil2(size)), value(cap + 1, 0)
    {
        if (initial != T{}) {
            std::fill(value.begin() + 1, value.end(), initial);
            for (std::size_t x = 1; x < cap; x++) { value[x + (x & -x)] += value[x]; }
        }
    }
    template <typename InIt>
    Fenwick(const InIt first, const InIt last) : size(std::distance(first, last)), cap(ceil2(size)), value(cap + 1, 0)
    {
        std::copy(first, last, value.begin() + 1);
        for (std::size_t x = 1; x < cap; x++) { value[x + (x & -x)] += value[x]; }
    }
    void add(const std::size_t a, const T& val)
    {
        assert(a < size);
        for (std::size_t ind = a + 1; ind <= cap; ind += ind & (-ind)) { value[ind] += val; }
    }
    T sum(const std::size_t a) const
    {
        assert(a <= size);
        T sum{};
        for (std::size_t ind = a; ind != 0; ind &= ind - 1) { sum += value[ind]; }
        return sum;
    }
    T sum(const std::size_t l, const std::size_t r) const { return assert(l < r), assert(r <= size), sum(r) - sum(l); }
    std::size_t partitionPoint(const T val) const
    {
        if (val < 0) { return 0; }
        std::size_t x = 0;
        T offset = 0;
        for (std::size_t k = ((cap == size) ? cap : cap / 2); k != 0; k >>= 1) {
            if (x + k <= cap and value[x + k] + offset <= val) { offset += value[x + k], x += k; }
        }
        return std::min(x, size);
    }
    friend std::ostream& operator<<(std::ostream& os, const Fenwick& fw)
    {
        os << "[";
        for (std::size_t i = 0; i < fw.size; i++) { os << fw.sum(i, i + 1) << (i + 1 == fw.size ? "" : ","); }
        return (os << "]\n");
    }

private:
    const std::size_t size, cap;
    std::vector<T> value;
};
// clang-format on
int main()
{
    const int n  = read<int>();
    const auto p = readVec<int>(n);
    std::vector<int> ind(n);
    std::iota(ind.begin(), ind.end(), 0);
    std::sort(ind.begin(), ind.end(), [&](const int i, const int j) { return p[i] > p[j]; });
    ll ans = 0;
    Fenwick<int> bit(n);
    for (const int i : ind) {
        const int v = p[i];
        int l1      = -1;
        for (int r1 = i + 1; r1 - l1 > 1;) {
            const int m1                        = (l1 + r1) / 2;
            (bit.sum(m1, i + 1) == 0 ? r1 : l1) = m1;
        }
        int l2 = -1;
        for (int r2 = i + 1; r2 - l2 > 1;) {
            const int m2                        = (l2 + r2) / 2;
            (bit.sum(m2, i + 1) <= 1 ? r2 : l2) = m2;
        }
        int r1 = n + 1;
        for (int l1 = i; r1 - l1 > 1;) {
            const int m1                    = (l1 + r1) / 2;
            (bit.sum(i, m1) == 0 ? l1 : r1) = m1;
        }
        int r2 = n + 1;
        for (int l2 = i; r2 - l2 > 1;) {
            const int m2                    = (l2 + r2) / 2;
            (bit.sum(i, m2) <= 1 ? l2 : r2) = m2;
        }
        bit.add(i, 1);
        r1--, r2--;
        const int num = (l1 - l2) * (r1 - i) + (r2 - r1) * (i - l1);
        ans += (ll)v * num;
    }
    std::cout << ans << std::endl;

    return 0;
}


Measured memory_bytes: 1664