#include <bits/stdc++.h>
using namespace std;
#define int long long
//TEMPLATE START---------------8<---------------8<---------------8<---------------8<---------------//
typedef long long ll;       typedef long double ld;  typedef pair<int,int> pii; typedef pair<ll,ll> pll;  typedef vector<int> vi;   typedef vector<ll> vl;
typedef vector<string> vst; typedef vector<bool> vb; typedef vector<ld> vld;    typedef vector<pii> vpii; typedef vector<pll> vpll; typedef vector<vector<int> > vvi;
const int INF = (0x7FFFFFFFL); const ll INFF = (0x7FFFFFFFFFFFFFFFL); const string ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
const int MOD = 1e9 + 7;       const int MODD = 998244353;            const string alphabet = "abcdefghijklmnopqrstuvwxyz";
const double PI = acos(-1.0);  const double EPS = 1e-9;               const string Alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
int dx[9] = { 1, 0, -1,  0,  1, -1, -1, 1, 0 };
int dy[9] = { 0, 1,  0, -1, -1, -1,  1, 1, 0 };
#define ln '\n'
#define scnaf scanf
#define sacnf scanf
#define sancf scanf
#define SS(type, ...)type __VA_ARGS__;MACRO_VAR_Scan(__VA_ARGS__);
template<typename T> void MACRO_VAR_Scan(T& t){cin >> t;}template<typename First, typename...Rest> void MACRO_VAR_Scan(First& first, Rest&...rest){cin >> first;MACRO_VAR_Scan(rest...);}
#define SV(type,c,n) vector<type> c(n);for(auto& i:c)cin >> i;
#define SVV(type,c,n,m) vector<vector<type>> c(n,vector<type>(m));for(auto& r:c)for(auto& i:r)cin >> i;
template<class T,class U>ostream &operator<<(ostream &o,const pair<T,U>&j){o<<"{"<<j.first<<", "<<j.second<<"}";return o;}
template<class T,class U>ostream &operator<<(ostream &o,const map<T,U>&j){o<<"{";for(auto t=j.begin();t!=j.end();++t)o<<(t!=j.begin()?", ":"")<<*t;o<<"}";return o;}
template<class T>ostream &operator<<(ostream &o,const set<T>&j){o<<"{";for(auto t=j.begin();t!=j.end();++t)o<<(t!=j.begin()?", ":"")<<*t;o<<"}";return o;}
template<class T>ostream &operator<<(ostream &o,const vector<T>&j){o<<"{";for(int i=0;i<(int)j.size();++i)o<<(i>0?", ":"")<<j[i];o<<"}";return o;}
inline int print(void){cout << endl; return 0;}
template<class Head> int print(Head&& head){cout << head;print();return 0;} template<class Head,class... Tail> int print(Head&& head,Tail&&... tail){cout<<head<<" ";print(forward<Tail>(tail)...);return 0;}
inline int debug(void){cerr << endl; return 0;}
template<class Head> int debug(Head&& head){cerr << head;debug();return 0;} template<class Head,class... Tail> int debug(Head&& head,Tail&&... tail){cerr<<head<<" ";debug(forward<Tail>(tail)...);return 0;}
template<typename T> void PA(T &a){int ASIZE=sizeof(a)/sizeof(a[0]);for(int ii=0;ii<ASIZE;++ii){cout<<a[ii]<<" \n"[ii==ASIZE-1];}}
template<typename T> void PV(T &v){int VSIZE=v.size();for(int ii=0;ii<VSIZE;++ii){cout<<v[ii]<<" \n"[ii==VSIZE-1];}}
#define ER(x)  cerr << #x << " = " << (x) << endl;
#define ERV(v) {cerr << #v << " : ";for(const auto& xxx : v){cerr << xxx << " ";}cerr << "\n";}
inline int YES(bool x){cout<<((x)?"YES":"NO")<<endl;return 0;} inline int Yes(bool x){cout<<((x)?"Yes":"No")<<endl;return 0;}  inline int yes(bool x){cout<<((x)?"yes":"no")<<endl;return 0;}
inline int yES(bool x){cout<<((x)?"yES":"nO")<<endl;return 0;} inline int Yay(bool x){cout<<((x)?"Yay!":":(")<<endl;return 0;}
template<typename A,typename B> void sankou(bool x,A a,B b){cout<<((x)?(a):(b))<<endl;}
#define _overload3(_1,_2,_3,name,...) name
#define _REP(i,n) REPI(i,0,n)
#define REPI(i,a,b) for(ll i=ll(a);i<ll(b);++i)
#define REP(...) _overload3(__VA_ARGS__,REPI,_REP,)(__VA_ARGS__)
#define _RREP(i,n) RREPI(i,n,0)
#define RREPI(i,a,b) for(ll i=ll(a);i>=ll(b);--i)
#define RREP(...) _overload3(__VA_ARGS__,RREPI,_RREP,)(__VA_ARGS__)
#define EACH(e,v) for(auto& e : v)
#define PERM(v) sort((v).begin(),(v).end());for(bool c##p=1;c##p;c##p=next_permutation((v).begin(),(v).end()))
#define ADD(a,b) a=(a+ll(b))%MOD
#define MUL(a,b) a=(a*ll(b))%MOD
inline ll MOP(ll x,ll n,ll m=MOD){ll r=1;while(n>0){if(n&1)(r*=x)%=m;(x*=x)%=m;n>>=1;}return r;}
inline ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}inline ll lcm(ll a,ll b){return a*b/gcd(a,b);}inline ll POW(ll a,ll b){ll c=1ll;do{if(b&1)c*=1ll*a;a*=1ll*a;}while(b>>=1);return c;}
template<typename T,typename A,typename B> inline bool between(T x,A a,B b) {return ((a<=x)&&(x<b));}template<class T> inline T sqr(T x){return x*x;}
template<typename A,typename B> inline bool chmax(A &a,const B &b){if(a<b){a=b;return 1;}return 0;}
template<typename A,typename B> inline bool chmin(A &a,const B &b){if(a>b){a=b;return 1;}return 0;}
#define tmax(x,y,z) max((x),max((y),(z)))
#define tmin(x,y,z) min((x),min((y),(z)))
#define PB push_back
#define MP make_pair
#define MT make_tuple
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define SORT(v) sort((v).begin(),(v).end())
#define RSORT(v) sort((v).rbegin(),(v).rend())
#define EXIST(s,e) (find((s).begin(),(s).end(),(e))!=(s).end())
#define EXISTST(s,c) (((s).find(c))!=string::npos)
#define POSL(x,val) (lower_bound(x.begin(),x.end(),val)-x.begin())
#define POSU(x,val) (upper_bound(x.begin(),x.end(),val)-x.begin())
#define GEQ(x,val) (int)(x).size() - POSL((x),(val))
#define GREATER(x,val) (int)(x).size() - POSU((x),(val))
#define LEQ(x,val) POSU((x),(val))
#define LESS(x,val) POSL((x),(val))
#define SZV(a) int((a).size())
#define SZA(a) sizeof(a)/sizeof(a[0])
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
#define MEMINF(a) memset(a,0x3f,sizeof(a))
#define FILL(a,b) memset(a,b,sizeof(a))
#define UNIQUE(v) sort((v).begin(),(v).end());(v).erase(unique((v).begin(),(v).end()),(v).end())
struct abracadabra{
  abracadabra(){
    cin.tie(0); ios::sync_with_stdio(0);
    cout << fixed << setprecision(20);
    cerr << fixed << setprecision(5);
  };
} ABRACADABRA;

//TEMPLATE END---------------8<---------------8<---------------8<---------------8<---------------//

/*
・遅延評価セグメント木
	> query, update O(logN)
[引数]
LazySegmentTree<Monoid, OperatorMonoid> seg(sz, f, g, h, d1, d0, v, p);
> sz : 要素数
>  f : 要素と要素をマージする関数
>  g : 要素に作用素を作用させる関数
>  h : 作用素と作用素をマージする関数
> d1 : 要素のモノイド
> d0 : 作用素のモノイド
>  v : 初期化用の配列
>  p : 区間に対する操作が要素数に比例して変化する場合 ( p(a, b) = g(a, a, ..., a) [aはb個] )
[備考]
以下の3つの条件を満たすときに使える
1. g(f(a, b), c) = f(g(a, c), g(b, c))
( 1'. g(f(a, b), p(c, d)) = f(g(a, p(c, d / 2)), g(b, p(c, d / 2))) )
2. g(g(a, b), c) = g(a, h(b, c))
3. g(a, d0) = a
[典型例]
> 区間加算 -> 区間和
LazySegmentTree<ll> seg(N, plus<ll>(), plus<ll>(), plus<ll>(), 0, 0, vl(N,0), multiplies<ll>());
> 区間加算 -> 区間最小
LazySegmentTree<ll> seg(N, [](ll a,ll b){return min(a,b);}, plus<ll>(), plus<ll>(), INFF, 0);
> 区間更新 -> 区間和
LazySegmentTree<ll> seg(N, plus<ll>(), [](ll a,ll b){return b;}, [](ll a,ll b){return b;}, 0, INFF, vl(N,0), multiplies<ll>());
> 区間更新 -> 区間最小
LazySegmentTree<ll> seg(N, [](ll a,ll b){return min(a,b);}, [](ll a,ll b){return b;}, [](ll a,ll b){return b;}, INFF, INFF);
[使用例]
seg.update(l, r, x);			// 半開区間[l, r)に作用素xを作用
seg.query(l, r);					// 半開区間[l, r)に対する演算の結果
seg[k];										// k番目の要素を取得
*/

template <typename Monoid, typename OperatorMonoid = Monoid> struct LazySegmentTree {

  typedef function< Monoid(Monoid, Monoid) > F;
  typedef function< Monoid(Monoid, OperatorMonoid) > G;
  typedef function< OperatorMonoid(OperatorMonoid, OperatorMonoid) > H;
  typedef function< OperatorMonoid(OperatorMonoid, int) > P;

  int sz;
  F f;
  G g;
  H h;
  P p;
  Monoid d1;
  OperatorMonoid d0;
  vector< Monoid > dat;
  vector< OperatorMonoid > laz;

  LazySegmentTree(int n, F f, G g, H h, Monoid d1, OperatorMonoid d0,
              vector< Monoid > v = vector< Monoid >(), P p = [] (OperatorMonoid a, int b) { return a; })
              : f(f), g(g), h(h), d1(d1), d0(d0), p(p) {
    sz = 1; while (sz < n) sz <<= 1;
    dat.assign(2 * sz - 1, 0);
    laz.assign(2 * sz - 1, d0);
    if (n == (int)v.size()) build(n, v);
  }

  void build(int n, vector<Monoid> &v) {
    for (int i = 0; i < n; i++)
      dat[i + sz - 1] = v[i];
    for (int i = sz - 2; i >= 0; i--)
      dat[i] = f(dat[i * 2 + 1], dat[i * 2 + 2]);
  }

  inline void eval(int len, int k) {
    if (laz[k] == d0) return;
    if (k * 2 + 1 < sz * 2 - 1) {
      laz[k * 2 + 1] = h(laz[k * 2 + 1], laz[k]);
      laz[k * 2 + 2] = h(laz[k * 2 + 2], laz[k]);
    }
    dat[k] = g(dat[k], p(laz[k], len));
    laz[k] = d0;
  }

  Monoid update(int a, int b, OperatorMonoid x, int k, int l, int r) {
    eval(r - l, k);
    if(r <= a || b <= l) return dat[k];
    if(a <= l && r <= b) {
      laz[k] = h(laz[k], x);
      return g(dat[k], p(laz[k], r - l));
    }
    return dat[k] = f(update(a, b, x, k * 2 + 1, l, (l + r) / 2),
		    update(a, b, x, k * 2 + 2, (l + r) / 2, r));
  }

  Monoid update(int a, int b, OperatorMonoid x) {
    return update(a, b, x, 0, 0, sz);
  }

  Monoid query(int a, int b, int k, int l, int r) {
    eval(r - l, k);
    if (r <= a || b <= l) return d1;
    if (a <= l && r <= b) return dat[k];
    Monoid vl = query(a, b, k * 2 + 1, l, (l + r) / 2);
    Monoid vr = query(a, b, k * 2 + 2, (l + r) / 2, r);
    return f(vl, vr);
  }

  Monoid query(int a, int b) {
    return query(a, b, 0, 0, sz);
  }

  Monoid operator[](const int &k) {
    return query(k, k + 1);
  }

  void debug() {
    print("dat:",dat);
    print("laz:",laz);
  }

};

const ll MAX = 1LL << 50;

signed main() {

  SS(int, N, Q, A, B);
  --A, --B;
  SV(int, X, Q);

  LazySegmentTree<ll> seg1(N, [](ll a,ll b){return min(a,b);}, plus<ll>(), plus<ll>(), INFF, 0);
  LazySegmentTree<ll> seg2(N, [](ll a,ll b){return min(a,b);}, plus<ll>(), plus<ll>(), INFF, 0);

  REP(i, N) {
    if (i == B) {
      seg1.update(i, i + 1,  i);
      seg2.update(i, i + 1, -i);
    } else {
      seg1.update(i, i + 1, MAX + i);
      seg2.update(i, i + 1, MAX - i);
    }
  }

  int prv = A;
  REP(i, Q) {
    int nxt = X[i] - 1;

    ll tmp = min<ll>(seg2.query(0, nxt) + nxt, seg1.query(nxt, N) - nxt);

    seg1.update(0, N, abs(nxt - prv));
    seg2.update(0, N, abs(nxt - prv));

    ll s1 = seg1.query(prv, prv + 1) - prv;
    if (tmp < s1) seg1.update(prv, prv + 1, tmp - s1);
    ll s2 = seg2.query(prv, prv + 1) + prv;
    if (tmp < s2) seg2.update(prv, prv + 1, tmp - s2);

    prv = nxt;
  }

  ll res = INFF;
  REP(i, N) chmin(res, seg1.query(i, i + 1) - i);
  print(res);

}


Measured memory_bytes: 20224