#include <bits/stdc++.h>
#pragma GCC diagnostic ignored "-Wsign-compare"
#pragma GCC diagnostic ignored "-Wsign-conversion"

#define NDEBUG
using i32 = int32_t;
using i64 = int64_t;
using u32 = uint32_t;
using u64 = uint64_t;
using uint = unsigned int;
using usize = std::size_t;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
template<typename T> constexpr T popcount(const T u) { return u ? static_cast<T>(__builtin_popcountll(static_cast<u64>(u))) : static_cast<T>(0); }
template<typename T> constexpr T log2p1(const T u) { return u ? static_cast<T>(64 - __builtin_clzll(static_cast<u64>(u))) : static_cast<T>(0); }
template<typename T> constexpr T msbp1(const T u) { return log2p1(u); }
template<typename T> constexpr T lsbp1(const T u) { return __builtin_ffsll(u); }
template<typename T> constexpr T clog(const T u) { return u ? log2p1(u - 1) : static_cast<T>(u); }
template<typename T> constexpr bool ispow2(const T u) { return u and (static_cast<u64>(u) & static_cast<u64>(u - 1)) == 0; }
template<typename T> constexpr T ceil2(const T u) { return static_cast<T>(1) << clog(u); }
template<typename T> constexpr T floor2(const T u) { return u == 0 ? static_cast<T>(0) : static_cast<T>(1) << (log2p1(u) - 1); }
template<typename T> constexpr bool btest(const T mask, const usize ind) { return ((static_cast<u64>(mask) >> ind) & static_cast<u64>(1)); }
template<typename T> constexpr T bcut(const T mask, const usize ind) { return ind == 0 ? static_cast<T>(0) : static_cast<T>((static_cast<u64>(mask) << (64 - ind)) >> (64 - ind)); }
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); }
constexpr unsigned int mod                  = 1000000007;
template<typename T> constexpr T inf_v      = std::numeric_limits<T>::max() / 4;
template<typename Real> constexpr Real pi_v = Real{3.141592653589793238462643383279502884};


/**
 * http://xoshiro.di.unimi.it/xoshiro128starstar.c
 * http://xoshiro.di.unimi.it/xoshiro256starstar.c
 * http://xoshiro.di.unimi.it/splitmix64.c
 */
class xoshiro
{
public:
    using result_type = uint32_t;
    static constexpr result_type min() { return std::numeric_limits<result_type>::min(); }
    static constexpr result_type max() { return std::numeric_limits<result_type>::max(); }
    xoshiro() : xoshiro(std::random_device{}()) {}
    xoshiro(uint64_t seed)
    {
        uint64_t z = 0;
        for (int i = 0; i < 4; i++) { z = (seed += 0x9e3779b97f4a7c15), z = (z ^ (z >> 33)) * 0x62A9D9ED799705F5, z = (z ^ (z >> 28)) * 0xCB24D0A5C88C35B3, s[i] = static_cast<result_type>(z >> 32); }
    }
    result_type operator()()
    {
        const result_type result = rotl(s[1] * 5, 7) * 9, t = s[1] << 9;
        return s[2] ^= s[0], s[3] ^= s[1], s[1] ^= s[2], s[0] ^= s[3], s[2] ^= t, s[3] = rotl(s[3], 11), result;
    }
    void discard(const usize rep)
    {
        for (usize i = 0; i < rep; i++) { (*this)(); }
    }

private:
    result_type s[4];
    static result_type rotl(const result_type x, const int k) { return (x << k) | (x >> (32 - k)); }
};
class xoshiro_64
{
public:
    using result_type = uint64_t;
    static constexpr result_type min() { return std::numeric_limits<result_type>::min(); }
    static constexpr result_type max() { return std::numeric_limits<result_type>::max(); }
    xoshiro_64() : xoshiro_64(std::random_device{}()) {}
    xoshiro_64(uint64_t seed)
    {
        uint64_t z = 0;
        for (int i = 0; i < 4; i++) { z = (seed += 0x9e3779b97f4a7c15), z = (z ^ (z >> 30)) * 0xbf58476d1ce4e5b9, z = (z ^ (z >> 27)) * 0x94d049bb133111eb, s[i] = static_cast<result_type>(z ^ (z >> 31)); }
    }
    result_type operator()()
    {
        const result_type result = rotl(s[1] * 5, 7) * 9, t = s[1] << 17;
        return s[2] ^= s[0], s[3] ^= s[1], s[1] ^= s[2], s[0] ^= s[3], s[2] ^= t, s[3] = rotl(s[3], 45), result;
    }
    void discard(const usize rep)
    {
        for (usize i = 0; i < rep; i++) { (*this)(); }
    }

private:
    result_type s[4];
    static result_type rotl(const result_type x, const int k) { return (x << k) | (x >> (64 - k)); }
};
template<typename Rng>
class rng_base
{
public:
    using rng_type    = Rng;
    using result_type = typename rng_type::result_type;
    static constexpr result_type min() { return rng_type::min(); }
    static constexpr result_type max() { return rng_type::max(); }
    rng_base() : rng_base(std::random_device{}()) {}
    rng_base(const u64 seed) : rng(seed) {}
    ~rng_base() = default;
    result_type operator()() { return rng(); }
    template<typename Int>
    Int uniform_int(const Int max)
    {
        static_assert(std::is_integral<Int>::value, "Integer type is needed.");
        if (ispow2(max + 1)) { return static_cast<Int>(rng() & max); }
        const result_type mask = static_cast<result_type>(ceil2(static_cast<u64>(max + 1))) - 1;
        while (true) {
            const Int ans = static_cast<Int>(rng() & mask);
            if (ans <= max) { return ans; }
        }
    }
    template<typename Int> Int uniform_int(const Int min, const Int max) { return min + uniform_int(static_cast<Int>(max - min)); }
    bool uniform_bool() { return uniform_int<bool>(0, 1); }
    template<typename Real>
    Real uniform_real()
    {
        static_assert(std::is_floating_point<Real>::value, "FloatingPoint type is needed.");
        return static_cast<Real>(uniformInt(~static_cast<result_type>(0)) / static_cast<Real>(~static_cast<result_type>(0)));
    }
    template<typename Real> Real uniform_real(const Real min, const Real max) { return assert(min <= max), uniform_real<Real>() * (max - min) + min; }
    template<typename Int> std::pair<Int, Int> uniform_int_pair(const Int min, const Int max) { return std::minmax(uniform_int(min, max), uniform_int(min, max)); }
    template<typename Int>
    std::vector<Int> uniform_int_vec(const std::size_t size, const Int min, const Int max)
    {
        std::vector<Int> v(size);
        for (std::size_t i = 0; i < size; i++) { v[i] = uniformInt(min, max); }
        return v;
    }
    template<typename Real>
    std::vector<Real> uniform_real_vec(const std::size_t size, const Real min, const Real max)
    {
        std::vector<Real> v(size);
        for (std::size_t i = 0; i < size; i++) { v[i] = uniformReal(min, max); }
        return v;
    }
    void discard(const usize rep) { rng.discard(rep); }

private:
    Rng rng;
};
using rng_mt        = rng_base<std::mt19937>;
using rng_mt64      = rng_base<std::mt19937_64>;
using rng_xoshiro   = rng_base<xoshiro>;
using rng_xoshiro64 = rng_base<xoshiro_64>;
rng_mt g_rng_mt;
rng_mt64 g_rng_mt64;
rng_xoshiro g_rng_xo;
rng_xoshiro64 g_rng_xo64;
template<typename T>
T read()
{
    T v;
    return std::cin >> v, v;
}
template<typename T>
std::vector<T> read_vec(const std::size_t size)
{
    std::vector<T> v(size);
    for (auto& e : v) { std::cin >> e; }
    return v;
}
#define SHOW(...) static_cast<void>(0)
template<typename T>
std::vector<T> make_v(const std::size_t size, T v) { return std::vector<T>(size, v); }
template<class... Args>
auto make_v(const std::size_t size, Args... args) { return std::vector<decltype(make_v(args...))>(size, make_v(args...)); }

template<typename MonoidAct>
class lazyseg
{
public:
    using monoid_act_type      = MonoidAct;
    using value_monoid_type    = typename monoid_act_type::value_monoid_type;
    using operator_monoid_type = typename monoid_act_type::operator_monoid_type;
    using value_type           = typename value_monoid_type::value_type;
    using operator_type        = typename operator_monoid_type::operator_type;
    lazyseg(const usize sz, const value_type initial = value_monoid_type::id()) : sz{sz}, depth{clog(sz)}, half{static_cast<usize>(1) << depth}, val(half << 1, value_monoid_type::id()), op(half << 1, operator_monoid_type::id())
    {
        if (initial != value_monoid_type::id()) {
            std::fill(val.begin() + half, val.end(), initial);
            for (usize i = half - 1; i >= 1; i--) { up(i); }
        }
    }
    template<typename InIt>
    lazyseg(const InIt first, const InIt last) : sz{static_cast<usize>(std::distance(first, last))}, depth{clog(sz)}, half{static_cast<usize>(1) << depth}, val(half << 1, value_monoid_type::id()), op(half << 1, operator_monoid_type::id())
    {
        std::copy(first, last, val.begin() + half);
        for (usize i = half - 1; i >= 1; i--) { up(i); }
    }
    value_type get(const usize a) { return assert(a < sz), fold(a, a + 1); }
    void set(usize a, const value_type& v)
    {
        assert(a < sz);
        top_down(a += half), top_down(a + 1), op[a] = operator_monoid_type::id(), val[a] = v;
        while (a >>= 1) { up(a); }
    }
    value_type fold(usize l, usize r)
    {
        assert(l < r), assert(r <= sz);
        top_down(l += half), top_down(r += half);
        value_type accl = value_monoid_type::id(), accr = value_monoid_type::id();
        for (; l < r; l >>= 1, r >>= 1) {
            if (l & 1) { accl = value_monoid_type::merge(accl, val[l++]); }
            if (r & 1) { accr = value_monoid_type::merge(val[--r], accr); }
        }
        return value_monoid_type::merge(accl, accr);
    }
    void act(usize l, usize r, const operator_type& f)
    {
        assert(l < r), assert(r <= sz);
        const usize lin = l + half, rin = r + half;
        top_down(l += half), top_down(r += half);
        for (usize ls = 1, rs = 1; l < r; l >>= 1, r >>= 1, ls <<= 1, rs <<= 1) {
            if (l & 1) { update(l++, f, ls); }
            if (r & 1) { update(--r, f, rs); }
        }
        bottom_up(lin), bottom_up(rin);
    }
    friend std::ostream& operator<<(std::ostream& os, lazyseg& lseg)
    {
        os << "[";
        for (usize i = 0; i < lseg.sz; i++) { os << lseg.get(i) << (i + 1 == lseg.sz ? "" : ","); }
        return (os << "]\n");
    }

private:
    void up(const usize i) { val[i] = value_monoid_type::merge(val[i << 1], val[i << 1 | 1]); }
    void update(const usize a, const operator_type& f, const usize l) { op[a] = operator_monoid_type::compose(f, op[a]), val[a] = monoid_act_type::apply(f, val[a], l); }
    void down(const usize a, const usize l) { update(a << 1, op[a], l >> 1), update(a << 1 | 1, op[a], l >> 1), op[a] = operator_monoid_type::id(); }
    void top_down(const usize a)
    {
        const usize b = (a / (a & -a)) >> 1;
        for (usize i = 0, l = half; i < depth; i++, l >>= 1) {
            const usize v = a >> (depth - i);
            if (v > b) { break; }
            down(v, l);
        }
    }
    void bottom_up(usize a)
    {
        a = (a / (a & -a)) >> 1;
        for (; a >= 1; a >>= 1) { up(a); }
    }
    const usize sz, depth, half;
    std::vector<value_type> val;
    std::vector<operator_type> op;
};
template<typename Element>
struct plus
{
    using element_type  = Element;
    using operator_type = element_type;
    plus()              = delete;
    static operator_type compose(const operator_type& a, const operator_type& b) { return a + b; }
    static constexpr operator_type id() { return operator_type{}; }
};

template<typename Element>
struct min
{
    using element_type = Element;
    using value_type   = element_type;
    min()              = delete;
    static value_type merge(const value_type& a, const value_type& b) { return std::min(a, b); }
    static constexpr value_type id() { return inf_v<value_type>; }
};
template<typename ValueElement, typename OperatorElement>
struct min_plus
{
    using value_element_type    = ValueElement;
    using operator_element_type = OperatorElement;
    using value_monoid_type     = min<value_element_type>;
    using operator_monoid_type  = plus<operator_element_type>;
    using value_type            = typename value_monoid_type::value_type;
    using operator_type         = typename operator_monoid_type::operator_type;
    min_plus()                  = delete;
    template<typename Ind>
    static value_type apply(const operator_type& f, const value_type& x, const Ind) { return std::min(static_cast<value_type>(f) + x, value_monoid_type::id()); }
};
int main()
{
    const auto N = read<usize>(), Q = read<usize>(), A = read<usize>() - 1, B = read<usize>() - 1;
    std::vector<usize> x{A, B};
    for (usize i = 0; i < Q; i++) { x.push_back(read<usize>() - 1); }
    SHOW(x);
    lazyseg<min_plus<ll, ll>> dp(N, inf_v<ll>), m(N, inf_v<ll>), p(N, inf_v<ll>);
    dp.set(x[0], 0LL), m.set(x[0], -x[0]), p.set(x[0], x[0]);
    for (usize i = 1; i <= Q; i++) {
        const ll d   = std::abs((ll)x[i + 1] - (ll)x[i]);
        const ll min = std::min(m.fold(0, x[i + 1] + 1) + (ll)x[i + 1], p.fold(x[i + 1], N) - (ll)x[i + 1]);
        dp.act(0, N, d), m.act(0, N, d), p.act(0, N, d);
        dp.set(x[i], std::min(min, dp.get(x[i]))), m.set(x[i], std::min(m.get(x[i]), min - (ll)x[i])), p.set(x[i], std::min(p.get(x[i]), min + (ll)x[i]));
        SHOW(dp);
    }
    std::cout << dp.fold(0, N) << std::endl;
    return 0;
}


Measured memory_bytes: 26608