#include <string>
#include <vector>
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<stack>
#include<queue>
#include<cmath>
#include<algorithm>
#include<functional>
#include<list>
#include<deque>
#include<bitset>
#include<set>
#include<map>
#include<unordered_map>
#include<unordered_set>
#include<cstring>
#include<sstream>
#include<complex>
#include<iomanip>
#include<numeric>
#include<cassert>
#define X first
#define Y second
#define pb push_back
#define rep(X,Y) for (int (X) = 0;(X) < (Y);++(X))
#define reps(X,S,Y) for (int (X) = S;(X) < (Y);++(X))
#define rrep(X,Y) for (int (X) = (Y)-1;(X) >=0;--(X))
#define rreps(X,S,Y) for (int (X) = (Y)-1;(X) >= (S);--(X))
#define repe(X,Y) for ((X) = 0;(X) < (Y);++(X))
#define peat(X,Y) for (;(X) < (Y);++(X))
#define all(X) (X).begin(),(X).end()
#define rall(X) (X).rbegin(),(X).rend()
#define eb emplace_back
#define UNIQUE(X) (X).erase(unique(all(X)),(X).end())
#define Endl endl

using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
template<class T> using vv=vector<vector<T>>;
template<class T> ostream& operator<<(ostream &os, const vector<T> &t) {
os<<"{"; rep(i,t.size()) {os<<t[i]<<",";} os<<"}"<<endl; return os;}
template<class S, class T> ostream& operator<<(ostream &os, const pair<S,T> &t) { return os<<"("<<t.first<<","<<t.second<<")";}
template<class T> inline bool MX(T &l,const T &r){return l<r?l=r,1:0;}
template<class T> inline bool MN(T &l,const T &r){return l>r?l=r,1:0;}
#define out(args...){vector<string> a_r_g_s=s_p_l_i_t(#args, ','); e_r_r(a_r_g_s.begin(), args); }
vector<string> s_p_l_i_t(const string &s, char c){vector<string> v;int d=0,f=0;string t;for(char c:s){if(!d&&c==',')v.pb(t),t="";else t+=c;if(c=='\"'||c=='\'')f^=1;if(!f&&c=='(')++d;if(!f&&c==')')--d;}v.pb(t);return move(v);}
void e_r_r(vector<string>::iterator it) {}
template<typename T, typename... Args> void e_r_r(vector<string>::iterator it, T a, Args... args){ if(*it==" 1"||*it=="1") cerr<<endl; else cerr << it -> substr((*it)[0] == ' ', it -> length()) << " = " << a << ", "; e_r_r(++it, args...);}
const ll MOD=1e9+7;
const int MAX_N=(1<<18);
const ll INF=1e18;
int nn=MAX_N;

struct Seg{
  ll mn,mnl,mnr;
  Seg(ll d=INF,int i=1e6){
    mn=d;
    mnl=d-i;
    mnr=d+i;
  }
  Seg (ll a,ll b,ll c):mn(a),mnl(b),mnr(c){};
  static Seg e;
};
vector<Seg> dat(2*MAX_N);
Seg Seg::e=Seg();

Seg operator+(Seg l,Seg r){
  return Seg(min(l.mn,r.mn),
	     min(l.mnl,r.mnl),
	     min(l.mnr,r.mnr));
}
ostream& operator<<(ostream &os, const Seg &t) { return os<<"["<<t.mn<<","<<t.mnl<<","<<t.mnr<<"]";}
template<class T=Seg> void upd(int k,T a,vector<T> &dat=dat){
  k+=dat.size()/2-1;
  dat[k]=a;
  while(k>0){
    k=(k-1)/2;
    dat[k]=dat[k*2+1]+dat[k*2+2];
  }
}

//(l,r,0,0,nn)
template<class T=Seg> T query(int a,int b,const vector<T> &dat=dat,int k=0,int l=0,int r=-1){
  if(r<0) r=dat.size()/2;
  if(r<=a || b<=l)return T::e;
  if(a<=l && r<=b) return dat[k];
  T lv=query(a,b,dat,k*2+1,l,(l+r)/2) ,rv= query(a,b,dat,k*2+2,(l+r)/2,r);
  return lv+rv;
}
int main(){
  ios_base::sync_with_stdio(false);
  cout<<fixed<<setprecision(0);
  int n,q,a,b;
  cin>>n>>q>>a>>b;
  vector<ll> xs(q);
  rep(i,q) cin>>xs[i];
  int prev=b;
  ll o=0;
  upd(a,Seg(0,a));
  //rep(i,n+1) cout<<query(i,i+1)<<",";cout<<endl;
  for(ll x:xs){
    ll ad=abs(x-prev);
    o+=ad;
    ll mnl=x+query(0,x).mnl;
    ll mnr=query(x,n+10).mnr-x;
    //out(mnl,mnr,1);
    upd(prev,Seg(min(mnl,mnr)-ad,prev));
    prev=x;
    //rep(i,n+1) cout<<query(i,i+1)<<",";cout<<o<<endl;
  }
  cout<<query(0,n+10).mn+o<<endl;
  return 0;
}


Measured memory_bytes: 14208