#include <iostream>
#include <iomanip>
#include <cstdio>
#include <string>
#include <cstring>
#include <deque>
#include <list>
#include <queue>
#include <stack>
#include <vector>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <complex>
#include <cmath>
#include <limits>
#include <cfloat>
#include <climits>
#include <ctime>
#include <cassert>
#include <numeric>
using namespace std;

#define rep(i,a,n) for(int (i)=(a); (i)<(n); (i)++)
#define repq(i,a,n) for(int (i)=(a); (i)<=(n); (i)++)
#define repr(i,a,n) for(int (i)=(a); (i)>=(n); (i)--)
#define all(v) begin(v), end(v)
#define pb(a) push_back(a)
#define fr first
#define sc second
#define INF 2000000000
#define int long long int

#define X real()
#define Y imag()
#define EPS (1e-10)
#define EQ(a,b) (abs((a) - (b)) < EPS)
#define EQV(a,b) ( EQ((a).X, (b).X) && EQ((a).Y, (b).Y) )
#define LE(n, m) ((n) < (m) + EPS)
#define LEQ(n, m) ((n) <= (m) + EPS)
#define GE(n, m) ((n) + EPS > (m))
#define GEQ(n, m) ((n) + EPS >= (m))

typedef vector<int> VI;
typedef vector<VI> MAT;
typedef pair<int, int> pii;
typedef long long ll;

typedef complex<double> P;
typedef pair<P, P> L;
typedef pair<P, double> C;

int dx[]={1, -1, 0, 0};
int dy[]={0, 0, 1, -1};
int const MOD = 1000000007;
ll mod_pow(ll x, ll n) {return (!n)?1:(mod_pow((x*x)%MOD,n/2)*((n&1)?x:1))%MOD;}
int madd(int a, int b) {return (a + b) % MOD;}
int msub(int a, int b) {return (a - b + MOD) % MOD;}
int mmul(int a, int b) {return (a * b) % MOD;}
int minv(int a) {return mod_pow(a, MOD-2);}
int mdiv(int a, int b) {return mmul(a, minv(b));}

namespace std {
    bool operator<(const P& a, const P& b) {
        return a.X != b.X ? a.X < b.X : a.Y < b.Y;
    }
}

int n, q, a, b;
int x[200010];
int node[1 << 19], node2[1 << 19];

// node [j] := dp[i][j] + j
// node2[j] := dp[i][j] - j にそれぞれ対応
struct LazySegTree {
    int SIZE;
    LazySegTree() {
        SIZE = 1;
        while(SIZE < n) SIZE *= 2;
        rep(i,0,2*SIZE) node[i] = node2[i] = INF;
    }

    // x 番目に要素 val を入れる
    // この時にインデックス分の足し引きをしておく
    void setnum(int x, int val) {
        int p = x + SIZE - 1;
        node [p] = val + x;
        node2[p] = val - x;
        while(p > 0) {
            p = (p - 1) / 2;
            node [p] = min(node [2*p+1], node [2*p+2]);
            node2[p] = min(node2[2*p+1], node2[2*p+2]);
        }
    }

    // x 番目の要素取得 (一番下の段を見れば良い)
    int getnum(int x) {
        return node[x + SIZE - 1] - x;
    }

    // [a, b) の最小値
    int getmin1(int a, int b, int l=0, int r=-1, int k=0) {
        if(r == -1) r = SIZE;
        if(r <= a || b <= l) return INF;
        if(a <= l && r <= b) return node[k];

        int ans = INF;
        ans = min(ans, getmin1(a, b, l, (l+r)/2, 2*k+1));
        ans = min(ans, getmin1(a, b, (l+r)/2, r, 2*k+2));
        return ans;
    }

    int getmin2(int a, int b, int l=0, int r=-1, int k=0) {
        if(r == -1) r = SIZE;
        if(r <= a || b <= l) return INF;
        if(a <= l && r <= b) return node2[k];

        int ans = INF;
        ans = min(ans, getmin2(a, b, l, (l+r)/2, 2*k+1));
        ans = min(ans, getmin2(a, b, (l+r)/2, r, 2*k+2));
        return ans;
    }
};

signed main() {
    cin >> n >> q >> a >> b;
    a--; b--;
    x[0] = b;
    rep(i,0,q) cin >> x[i+1], x[i+1]--;
    LazySegTree lz;
    lz.setnum(a, 0);
    int addall = 0;
    rep(i,0,q) {
        int diff = abs(x[i+1] - x[i]);

        // 前の x[i] 番目の値を取ってくる
        ll elem = lz.getnum(x[i]);

        // 0 <= j < x[i+1] について、min{ dp[i][j] + x[i+1] - j } を取る
        // dp[i][j] - j の部分に関しては SegTree で計算
        // (SegTree に全体加算は反映させないので diff 分引いてがんばる)
        elem = min(elem, lz.getmin2(0, x[i+1]) + x[i+1] - diff);

        // x[i+1] <= j < n について、min{ dp[i][j] - x[i+1] - j } を取る
        // dp[i][j] + j の部分に関しては SegTree で計算
        elem = min(elem, lz.getmin1(x[i+1], n) - x[i+1] - diff);
        lz.setnum(x[i], elem);
        addall += diff;
    }
    int ans = INF;
    rep(i,0,n) ans = min(ans, lz.getnum(i));
    cout << ans + addall << endl;
    return 0;
}

Measured memory_bytes: 9984