#define STOPIT
#include <bits/stdc++.h>
#define loop(n) for (int ngtkana_is_a_genius = 0; ngtkana_is_a_genius < int(n); ngtkana_is_a_genius++)
#define rep(i, begin, end) for (int i = int(begin); (i) < int(end); i++)
#define all(v) v.begin(), v.end()
#define rand(l, r) std::uniform_int_distribution<>(l, r)(mt)
using lint = long long;
auto mt = std::mt19937_64(std::random_device{}());
auto cmn = [](auto& a, auto b){ if (a > b) {a = b; return true;} return false; };
auto cmx = [](auto& a, auto b){ if (a < b) {a = b; return true;} return false; };
void debug_impl() { std::cerr << std::endl; }
template <typename Head, typename... Tail>
void debug_impl(Head head, Tail... tail) { std::cerr << " " << head; debug_impl(tail...); }
#ifndef STOPIT
#define debug(...)\
  do {\
    std::cerr << std::boolalpha << "[" << #__VA_ARGS__ << "]:";\
    debug_impl(__VA_ARGS__);\
    std::cerr << std::noboolalpha;\
  } while (false)
#else
#define debug(...) {}
#endif

template < typename Value, typename BinaryOp >
class segment_tree {
    int                  sz, n, N;
    BinaryOp             op;
    Value                id;
    std::vector< Value > table;

    auto& op_eq(Value& x, Value y) const
      { return x = op(x, y); }
    void merge(int u)
      { table.at(u) = op(table.at(2 * u), table.at(2 * u + 1)); }

  public:
    segment_tree(int sz, BinaryOp op, Value id):
      sz    (sz),
      n     (std::pow(2, int(std::log2(2 * sz - 1)))),
      N     (n * 2),
      op    (op),
      id    (id),
      table (N, id)
      {}

    auto& at(int i)       { return table.at(n + i); }
    auto& at(int i) const { return table.at(n + i); }
    auto collect() const {
      auto ret = std::vector<Value>(sz);
      for (auto i = 0; i < sz; i++)
        { ret.at(i) = at(i); }
      return ret;
    }
    auto query(int l, int r) const {
      auto const dfs = [&](auto&& f, int l, int r, int k, int L, int R) -> Value {
        return l <= L && R <= r
          ? table.at(k)
          : R <= l || r <= L
          ? id
          : op(
            f(f, l, r, 2 * k, L, (L + R) / 2),
            f(f, l, r, 2 * k + 1, (L + R) / 2, R)
          );
      };
      return dfs(dfs, l, r, 1, 0, n);
    }
    void build_oneline(int i)
      { for (i += n, i /= 2; i > 0; i /= 2) merge(i); }
    void build()
      { for (auto i = n - 1; i > 0; i--) merge(i); }
};

template<typename Value, typename BinaryOp>
auto make_segment_tree(int sz, BinaryOp op, Value id)
  { return segment_tree<Value, BinaryOp>(sz, std::move(op), id); }

template < typename Container, typename Value = typename Container::value_type, std::enable_if_t<!std::is_same< Container, std::string >::value, std::nullptr_t> = nullptr>
std::istream& operator>> (std::istream& is, Container& v)
  { for (auto & x : v) { is >> x; } return is; }

template < typename Container, typename Value = typename Container::value_type, std::enable_if_t<!std::is_same< Container, std::string >::value, std::nullptr_t> = nullptr >
std::ostream& operator<< (std::ostream& os, Container const& v) {
 os << "{";
  for (auto it = v.begin(); it != v.end(); it++)
    {os << (it != v.begin() ? "," : "") << *it;}
  return os << "}";
}

// require gcc >= 7.1.0
template < class ... Keys >
class fmt_t {
    using storage_t = std::tuple< Keys ... >;
    storage_t storage;
    static constexpr std::size_t N = sizeof ... (Keys);

    // is_exact_match_impl
    template < std::size_t I, class Value >
      auto is_exact_match_impl(long, Value) const
        { return false; }

    template < std::size_t I, class Value,
      std::enable_if_t<
        std::is_same< std::decay_t< Value > , char >::value
        == std::is_same< std::tuple_element_t< I, storage_t >, char >::value,
      std::nullptr_t > = nullptr,
      class = decltype(std::declval< Value >() == std::get< I >(std::declval< storage_t >())) >
      auto is_exact_match_impl(int, Value x) const
        { return x == std::get< I >(storage); }

    template < class Value, std::size_t ... Is >
      auto find_exact_match_impl(Value x, std::integer_sequence< std::size_t, Is ... >) const {
        auto ret = false;
        (void)std::initializer_list< std::nullptr_t >
          { (ret |= is_exact_match_impl< Is >(int{}, x), nullptr) ...  };
        return ret;
      }

    template < class Value >
      auto exists_exact_match(Value x) const
      {  return find_exact_match_impl(x, std::make_index_sequence< N >()); }

    // tuple_format_impl
    template < class Tuple,  std::size_t ... Is >
    std::string tuple_format_impl(const Tuple& tuple, std::integer_sequence< std::size_t, Is ... >) const {
      std::string ret = "(";
      (void)std::initializer_list< std::nullptr_t >
        { (ret = ret + (Is == 0 ? "" : ",") + format(std::get< Is >(tuple)), nullptr) ... };
      return ret + ")";
    }

    // usual_format
    template < class Value >
    std::string usual_format(long, Value x) const
      { return std::to_string(x); }

    template < class Value, std::enable_if_t< std::is_same< std::decay_t< Value >, char >::value, std::nullptr_t > = nullptr >
    std::string usual_format(int, Value c) const
      { return std::string{'\''} + std::string{c} + std::string{'\''}; }

    std::string usual_format(int, char const* s) const
      { return "\"" + std::string(s) + "\""; }

    std::string usual_format(int, std::string const s) const
      { return "\"" + s + "\""; }

    template < class Container, class = typename Container::value_type >
    std::string usual_format(int, Container const & v) const {
      return "{" + std::accumulate(v.begin(), v .end(), std::string{},
        [this](auto const& s, auto const x) { return s + (s.empty() ? "" : ",") + this->format(x); })
        + "}";
    }

    template < class Tuple, std::size_t N = std::tuple_size< Tuple >::value >
    std::string usual_format(int, Tuple const& tuple) const
      { return tuple_format_impl(tuple, std::make_index_sequence< N >()); }

    // format
    template < class Value > std::string format(Value&& x) const
      { return exists_exact_match(x) ? std::string{'_'} : usual_format(int{}, x); }

  public:
    fmt_t()=default;
    template < Keys ... > fmt_t(Keys&& ... keys ) : storage(keys ... ){}

    template < class Value > std::string operator()(Value&& x) const
      { return format(x); }
};
template < class ... Keys > auto fmt(Keys&& ... keys)
  { return fmt_t< Keys ... >(std::forward< Keys >(keys) ... ); }

int main() {
  std::cin.tie(0); std::cin.sync_with_stdio(false);
  int n, q, A, B;
  std::cin >> n >> q >> A >> B;
  A--,B--;
  std::vector<lint> pos(q);
  std::cin >> pos;
  for (lint & x : pos) x--;

  lint inf = std::numeric_limits<lint>::max();
  auto dp = make_segment_tree<lint>(n, [](lint x, lint y){ return std::min(x,y); }, inf);
  auto ep = dp;
  auto fp = dp;
  int prv = A;
  dp.at(B) = 0; dp.build_oneline(B);
  ep.at(B) = -B; ep.build_oneline(B);
  fp.at(B) = +B; fp.build_oneline(B);
  debug(fmt(inf)(dp.collect()));
  debug(fmt(inf)(ep.collect()));
  debug(fmt(inf)(fp.collect()));
  debug("");

  lint basic = 0;
  for (int crr : pos) {
    lint d = crr - prv;
    if (d < 0) d = -d;
    basic += d;
    lint x = ep.query(0, crr+1);
    if (x != inf) {
      debug(x,crr,d);
      x += crr - d;
      debug(x);
      cmn(dp.at(prv), x);
    }
    lint y = fp.query(crr,n);
    if (y != inf) {
      y += -crr - d;
      debug(y);
      cmn(dp.at(prv), y);
    }
    dp.build_oneline(prv);

    lint z = dp.at(prv);
    if (z != inf) {
      cmn(ep.at(prv), z-prv); ep.build_oneline(prv);
      cmn(fp.at(prv), z+prv); fp.build_oneline(prv);
    }

    debug(fmt(inf)(dp.collect()));
    debug(fmt(inf)(ep.collect()));
    debug(fmt(inf)(fp.collect()));
    debug("");
    prv = crr;
  }
  lint ans = dp.query(0,n);
  debug(ans,basic);
  ans += basic;
  std::cout << ans << std::endl;
  return 0;
}

Measured memory_bytes: 14080