Sasha and Dima want to buy two n-tier cakes. Each cake should consist of n different tiers: from the size of 1 to the size of n. Tiers should go in order from the smallest to the biggest (from top to bottom).

They live on the same street, there are 2 ⋅ n houses in a row from left to right. Each house has a pastry shop where you can buy a cake tier. Unfortunately, in each pastry shop you can buy only one tier of only one specific size: in the i-th house you can buy a tier of the size a_i (1 ≤ a_i ≤ n).

Since the guys carry already purchased tiers, and it is impossible to insert a new tier in the middle of the cake, they agreed to buy tiers from the smallest to the biggest. That is, each of them buys tiers in order: 1, then 2, then 3 and so on up to n.

Initially, Sasha and Dima are located near the first (leftmost) house. Output the minimum distance that they will have to walk in total to buy both cakes. The distance between any two neighboring houses is exactly 1.

Input

The first line of the input contains an integer number n — the number of tiers in each cake (1 ≤ n ≤ 10^5).

The second line contains 2 ⋅ n integers a_1, a_2, ..., a_{2n} (1 ≤ a_i ≤ n), where a_i is equal to the size of the tier, which can be bought in the i-th house. Remember that in each house you can buy only one tier. It is guaranteed that every number from 1 to n occurs in a exactly two times.

Output

Print one number — the minimum distance that the guys have to walk in total to buy both cakes. Guys can be near same house at the same time. They begin near the first (leftmost) house. Each of the guys should buy n tiers in ascending order of their sizes.

Examples

Input


3
1 1 2 2 3 3


Output


9


Input


2
2 1 1 2


Output


5


Input


4
4 1 3 2 2 3 1 4


Output


17

Note

In the first example, the possible optimal sequence of actions is:

  * Sasha buys a tier of size 1 near the 1-st house (a_1=1); 
  * Dima goes to the house 2; 
  * Dima buys a tier of size 1 near the 2-nd house (a_2=1); 
  * Sasha goes to the house 4; 
  * Sasha buys a tier of size 2 near the 4-th house (a_4=2); 
  * Sasha goes to the house 5; 
  * Sasha buys a tier of size 3 near the 5-th house (a_5=3); 
  * Dima goes to the house 3; 
  * Dima buys a tier of size 2 near the 3-rd house (a_3=2); 
  * Dima goes to the house 6; 
  * Dima buys a tier of size 3 near the 6-th house (a_6=3). 



So, Sasha goes the distance 3+1=4, and Dima goes the distance 1+1+3=5. In total, they cover a distance of 4+5=9. You can make sure that with any other sequence of actions they will walk no less distance.
/*
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......................................................................................................................................
 */

import java.io.IOException;
import java.io.InputStream;
import java.util.*;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

import static java.lang.Math.max;
import static java.lang.Math.min;
import static java.lang.Math.pow;
import static java.lang.Math.abs;

import static java.lang.String.format;


public class Main {
    public static int INT_INF=Integer.MAX_VALUE/2;
    public static void main(String[] args) {
        Scanner scanner=new Scanner();
        int n=scanner.nextInt();
        int[] a=new int[n<<1];
        for(int i=0;i<(n<<1);i++){
            a[i]=scanner.nextInt();
        }
        Map<Integer,Pair> map=new HashMap<>();
        for(int i=0;i<(n<<1);i++){
            Pair p=map.getOrDefault(a[i],new Pair(0,0));
            if(p.x==0){
                p.x=i;
            }else{
                p.y=i;
            }
            map.put(a[i],p);
        }
        long ans=0;
        int currentS=0,currentD=0;
        for(int i=0;i<n;i++){
            Pair p=map.get(i+1);
            if(abs(p.x-currentS)+abs(p.y-currentD)<=abs(p.x-currentD)+abs(p.y-currentS)){
                ans+=abs(p.x-currentS)+abs(p.y-currentD);
                currentS=p.x;
                currentD=p.y;
            }else{
                ans+=abs(p.x-currentD)+abs(p.y-currentS);
                currentS=p.y;
                currentD=p.x;
            }
        }
        put(ans);


    }
    static class Pair{
        int x,y;
        Pair(int x,int y){
            this.x=x;
            this.y=y;
        }
    }

    public static int upper_bound(long[] a,long val){
        return upper_bound(a,0,a.length,val);
    }
    public static int upper_bound(long[] a,int l,int r,long val){
        if(r-l==1){
            if(a[l]>val) return l;
            return r;
        }
        int mid=(l+r)/2;
        if(a[mid]>val){
            return upper_bound(a,l,mid,val);
        }else{
            return upper_bound(a,mid,r,val);
        }
    }
    public static <T> int upper_bound(T[] a,int l,int r,T val,Comparator<T> comparator){
        if(r-l==1){
            if(comparator.compare(a[l],val)>0) return l;
            return r;
        }
        int mid=(l+r)/2;
        if(comparator.compare(a[mid],val)>0){
            return upper_bound(a,l,mid,val,comparator);
        }else{
            return upper_bound(a,mid,r,val,comparator);
        }
    }
    public static int lower_bound(long[] a,long val){
        return lower_bound(a,0,a.length,val);
    }
    public static int lower_bound(long[] a,int l,int r,long val){
        if(r-l==1){
            if(a[l]<val) return r;
            return l;
        }
        int mid=(l+r)/2;
        if(a[mid]<val){
            return lower_bound(a,mid,r,val);
        }else{
            return lower_bound(a,l,mid,val);
        }

    }

    public static <T> int lower_bound(T[] a,int l,int r,T val,Comparator<T> comparator){
        if(r-l==1){
            if(comparator.compare(a[l],val)<0) return r;
            return l;
        }
        int mid=(l+r)/2;
        if(comparator.compare(a[mid],val)<0){
            return lower_bound(a,mid,r,val,comparator);
        }else{
            return lower_bound(a,l,mid,val,comparator);
        }
    }


    public static void print(Object object){
        System.out.print(object);
    }
    public static void put(Object object) {
        System.out.println(object);
    }
    public static void put(){
        System.out.println();
    }
    public static long min(long... longs){
        if(longs.length==0)throw new IllegalArgumentException("Argument.length==0");
        long min=Long.MAX_VALUE;
        for(int i=0;i<longs.length;i++){
            min=Math.min(min,longs[i]);
        }
        return min;
    }
    public static long max(long... longs){
        if(longs.length==0)throw new IllegalArgumentException("Argument.length==0");
        long max=Long.MIN_VALUE;
        for(int i=0;i<longs.length;i++){
            max=Math.max(max,longs[i]);
        }
        return max;
    }

    final static private class Scanner {
        private final InputStream in = System.in;
        private final byte[] buffer = new byte[1024];
        private int ptr = 0;
        private int buflen = 0;

        private boolean hasNextByte() {
            if (ptr < buflen) {
                return true;
            } else {
                ptr = 0;
                try {
                    buflen = in.read(buffer);
                } catch (IOException e) {
                    e.printStackTrace();
                }
                if (buflen <= 0) {
                    return false;
                }
            }
            return true;
        }

        private int readByte() {
            if (hasNextByte())
                return buffer[ptr++];
            else
                return -1;
        }

        private boolean isPrintableChar(int c) {
            return 33 <= c && c <= 126;
        }

        public boolean hasNext() {
            while (hasNextByte() && !isPrintableChar(buffer[ptr]))
                ptr++;
            return hasNextByte();
        }

        public String next() {
            if (!hasNext())
                throw new NoSuchElementException();
            StringBuilder sb = new StringBuilder();
            int b = readByte();
            while (isPrintableChar(b)) {
                sb.appendCodePoint(b);
                b = readByte();
            }
            return sb.toString();
        }

        public long nextLong() {
            if (!hasNext())
                throw new NoSuchElementException();
            long n = 0;
            boolean minus = false;
            int b = readByte();
            if (b == '-') {
                minus = true;
                b = readByte();
            }
            if (b < '0' || '9' < b) {
                throw new NumberFormatException();
            }
            while (true) {
                if ('0' <= b && b <= '9') {
                    n *= 10;
                    n += b - '0';
                } else if (b == -1 || !isPrintableChar(b)) {
                    return minus ? -n : n;
                } else {
                    throw new NumberFormatException();
                }
                b = readByte();
            }
        }

        public int nextInt() {
            long nl = nextLong();
            if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
                throw new NumberFormatException();
            return (int) nl;
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }
    }
    final static private class FixedPair {
        final private long x, y;
        final static public FixedPair ZEROS=new FixedPair(0,0);
        FixedPair(long x, long y) {
            this.x = x;
            this.y = y;
        }

        public long getX() {
            return x;
        }

        public long getY() {
            return y;
        }

        @Override
        public int hashCode() {
            return (int)x+(int)y;
        }

        @Override
        public boolean equals(Object obj) {
            boolean result=super.equals(obj);
            if(obj.getClass()!=this.getClass()){
                return false;
            }
            FixedPair pair=(FixedPair)obj;
            if(this.x==pair.x&&this.y==pair.y) return true;
            return false;
        }

        @Override
        public String toString() {
            return String.format("(%d,%d)", x, y);
        }
    }
    final static private class Tuple<T,V>{
        //immutabl1でないことに注意(T,Vがmutableの場合変更可能)
        final private T t;
        final private V v;
        Tuple(T t,V v){
            this.t=t;
            this.v=v;
        }

        public T getT() {
            return t;
        }

        public V getV() {
            return v;
        }

        @Override
        public int hashCode() {
            return (t.hashCode()+v.hashCode());
        }

        @Override
        @SuppressWarnings("unchecked")
        public boolean equals(Object obj) {
            if(obj.getClass()!=this.getClass()){
                return false;
            }
            Tuple<T,V> tuple=(Tuple<T, V>) obj;
            return tuple.t.equals(this.t)&&tuple.v.equals(this.v);
        }

        @Override
        public String toString() {
            return String.format("<Tuple>=<%s,%s>",t,v);
        }
    }
    final static private class Util {
        static long gcd(long a,long b){
            //最大公約数　
            if(a%b==0)return b;
            return gcd(b,a%b);
        }
        static long lcm(long a,long b){
            //最小公倍数
            long gcd=gcd(a,b);
            long result=b/gcd;
            return a*result;
        }
        static long kaijoMod(int n,int mod){
            if(n<1) return -1;
            long result=1;
            for(int i=n;i>1;i--){
                result*=i;
                result%=mod;
            }
            return result;
        }
        static <T extends Comparable<T>> Map<T,Integer> count(List<T> list){
            //副作用
            Collections.sort(list);
            Map<T,Integer> result=new HashMap<>();
            int l=0,r=0;
            while(l<list.size()){
                while(r<list.size()-1&&list.get(r).equals(r+1)){
                    r++;
                }
                result.put(list.get(r),r-l+1);
                r++;
                l=r;
            }
            return result;

        }
        static Map<Integer,Integer> count(int[] array){
            //副作用
            Arrays.sort(array);
            Map<Integer,Integer> result=new HashMap<>();
            int l=0,r=0;
            while(l<array.length){
                while(r<array.length-1&&array[r]==array[r+1]){
                    r++;
                }
                result.put(array[l],r-l+1);
                r++;
                l=r;
            }
            return result;
        }
        static <T> String toStringBWS(Iterable<T> iterable){
            Iterator<T> ite=iterable.iterator();
            return toStringBWS(ite);
        }
        static <T> String toStringBWS(Iterator<T> ite){
            StringBuilder sb=new StringBuilder();
            sb.append(ite.next());
            while(ite.hasNext()){
                sb.append(" ");
                sb.append(ite.next());
            }
            return sb.toString();
        }
        static int[] factoringInPrimeNumbers(long n,int size){
            //素因数分解
            //sizeがnに比べて小さい場合完全に素因数分解出来ていない可能性がある
            int[] result=new int[size];
            for(int i=2;n>1&&i< result.length;i++){
                while(n%i==0){
                    result[i]++;
                    n/=i;
                }
            }
            return result;

        }
    }
}
