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.
//package CodeforcesProject;


import java.io.*;
import java.lang.*;
import java.util.*;

public class Main {

    public static Input input;
    public static Output output;

    public static void main(String[] args) throws Exception {
        input = new Input();
        output = new Output();
        int quantity = input.ReadInt();
        int[] size = input.ReadArrayInt(" ");
        Integer[][] base = new Integer[quantity][2];
        for (int index = 0; index < quantity * 2; index++){
            if (base[size[index] - 1][0] == null) {
                base[size[index] - 1][0] = index;
            }else{
                base[size[index] - 1][1] = index;
            }
        }
        long answer = base[0][0] + base[0][1];
        for (int index = 1; index < quantity; index++){
            answer += (Math.abs(base[index][0] - base[index - 1][0]));
            answer += (Math.abs(base[index][1] - base[index - 1][1]));
        }
        System.out.println(answer);
    }
}

class method {

    public static int gcd(int a, int b) { // NOD
        if (b == 0) {
            return a;
        }
        return gcd(b, a % b);
    }

    public static long gcd(long a, long b) {
        if (b == 0) {
            return a;
        }
        return gcd(b, a % b);
    }

    public static int lcm(int a, int b) { // NOK
        return a / gcd(a, b) * b;
    }

    public static long lcm(long a, long b) {
        return a / gcd(a, b) * b;
    }

    public static void exit() throws Exception {
        Main.output.write.flush();
        Main.input.read.close();
        Main.output.write.close();
    }
}

class graph {

    private static int[][] base;
    private static boolean[] used;
    public static int quantity = 0;
    private static Integer[] pred;

    public static void start(int length) {
        used = new boolean[length];
        pred = new Integer[length];
    }

    public static void RibMatrixToDefault(int length) throws Exception {
        start(length);
        base = new int[length][];
        int FirstSize;
        int SecondSize;
        int[] rib;
        int[] FirstArray;
        int[] SecondArray;
        int[] NewFirstArray;
        int[] NewSecondArray;
        for (int i = 0; i < length; i++) {
            rib = Arrays.stream(Main.input.ReadArrayInt(" ")).map(element -> element - 1).toArray();
            FirstArray = base[rib[0]];
            SecondArray = base[rib[1]];
            if (FirstArray == null) {
                FirstSize = 0;
            } else {
                FirstSize = FirstArray.length;
            }
            if (SecondArray == null) {
                SecondSize = 0;
            } else {
                SecondSize = SecondArray.length;
            }
            NewFirstArray = new int[FirstSize + 2];
            NewSecondArray = new int[SecondSize + 2];
            for (int index = 0; index < Math.max(FirstSize, SecondSize); index++) {
                if (index < FirstSize) {
                    NewFirstArray[index] = FirstArray[index];
                }
                if (index < SecondSize) {
                    NewSecondArray[index] = SecondArray[index];
                }
            }
            NewFirstArray[FirstSize] = rib[1];
            NewSecondArray[SecondSize] = rib[0];
            NewFirstArray[FirstSize + 1] = 1;
            NewSecondArray[SecondSize + 1] = 1;
            base[rib[0]] = NewFirstArray;
            base[rib[1]] = NewSecondArray;
        }
    }

    public static void AdjacencyMatrixToDefault(int length, int dont) throws Exception {
        start(length);
        base = new int[length][];
        List<Integer> buffer = new ArrayList<>();
        int[] InputArray;
        for (int i = 0; i < length; i++) {
            InputArray = Main.input.ReadArrayInt(" ");
            for (int index = 0; index < length; index++) {
                if (i != index && InputArray[index] != dont) {
                    buffer.add(index);
                    buffer.add(InputArray[index]);
                }
            }
            base[i] = buffer.stream().mapToInt(element -> element).toArray();
            buffer.clear();
        }
    }

    public static void dfs(int position) throws Exception {
        used[position] = true;
        quantity++;
        int next;
        for (int index = 0; index < base[position].length; index += 2) {
            next = base[position][index];
            if (!used[next]) {
                pred[next] = position;
                dfs(next);
            } else {
                if (next != pred[position]) { // if cycle
                    throw new Exception();
                }
            }
        }
    }

    public static int dijkstra(int start, int stop, int size) {
        start--;
        stop--;
        int[] dist = new int[size];
        for (int i = 0; i < size; i++) {
            if (i != start) {
                dist[i] = Integer.MAX_VALUE;
            }
            pred[i] = start;
        }
        Queue<int[]> queue = new PriorityQueue<>((int[] first, int[] second) -> Integer.compare(first[1], second[1]));
        queue.add(new int[]{start, 0});
        int position;
        int[] GetQueue;
        while (queue.size() != 0) {
            GetQueue = queue.poll();
            position = GetQueue[0];
            if (GetQueue[1] > dist[position]) {
                continue;
            }
            for (int index = 0; index < base[position].length; index += 2) {
                if (dist[position] + base[position][index + 1] < dist[base[position][index]] && !used[base[position][index]]) {
                    dist[base[position][index]] = dist[position] + base[position][index + 1];
                    pred[base[position][index]] = position;
                    queue.add(new int[]{base[position][index], dist[base[position][index]]});
                }
            }
            used[position] = true;
        }
        return dist[stop] == Integer.MAX_VALUE ? -1 : dist[stop];
    }

    public static boolean FloydWarshall(int[][] base, int length, int dont) {
        for (int k = 0; k < length; k++) {
            for (int i = 0; i < length; i++) {
                for (int j = 0; j < length; j++) {
                    if (base[i][k] == dont || base[k][j] == dont) {
                        continue;
                    }
                    int total = base[i][k] + base[k][j];
                    if (base[i][j] != dont) {
                        base[i][j] = Math.min(base[i][j], total);
                    } else {
                        base[i][j] = total;
                    }
                }
            }
        }
        for (int index = 0; index < length; index++) {
            if (base[index][index] != 0) { // if cycle
                return false;
            }

        }
        return true;
    }
}

class FastSort {

    public static void SortWithoutReturn(int[] array, int ShellHeapMergeMyInsertionSort, int length) {
        sort(array, ShellHeapMergeMyInsertionSort, length);
    }

    public static int[] SortWithReturn(int[] array, int ShellHeapMergeMyInsertionSort, int length) {
        sort(array, ShellHeapMergeMyInsertionSort, length);
        return array;
    }

    private static void sort(int[] array, int ShellHeapMergeMyInsertionSort, int length) {
        if (ShellHeapMergeMyInsertionSort < 0 || ShellHeapMergeMyInsertionSort > 4) {
            Random random = new Random();
            ShellHeapMergeMyInsertionSort = random.nextInt(4);
        }
        if (ShellHeapMergeMyInsertionSort == 0) {
            ShellSort(array);
        } else if (ShellHeapMergeMyInsertionSort == 1) {
            HeapSort(array);
        } else if (ShellHeapMergeMyInsertionSort == 2) {
            MergeSort(array, 0, length - 1);
        } else if (ShellHeapMergeMyInsertionSort == 3) {
            StraightMergeSort(array, length);
        } else if (ShellHeapMergeMyInsertionSort == 4) {
            insertionSort(array);
        }
    }

    private static void StraightMergeSort(int[] array, int size) {
        if (size == 0) {
            return;
        }
        int length = (size / 2) + ((size % 2) == 0 ? 0 : 1);
        Integer[][] ZeroBuffer = new Integer[length + length % 2][2];
        Integer[][] FirstBuffer = new Integer[0][0];
        for (int index = 0; index < length; index++) {
            int ArrayIndex = index * 2;
            int NextArrayIndex = index * 2 + 1;
            if (NextArrayIndex < size) {
                if (array[ArrayIndex] > array[NextArrayIndex]) {
                    ZeroBuffer[index][0] = array[NextArrayIndex];
                    ZeroBuffer[index][1] = array[ArrayIndex];
                } else {
                    ZeroBuffer[index][0] = array[ArrayIndex];
                    ZeroBuffer[index][1] = array[NextArrayIndex];
                }
            } else {
                ZeroBuffer[index][0] = array[ArrayIndex];
            }
        }
        boolean position = false;
        int pointer0;
        int pointer;
        int pointer1;
        int number = 4;
        int NewPointer;
        int count;
        Integer[][] NewBuffer;
        Integer[][] OldBuffer;
        length = (size / 4) + ((size % 4) == 0 ? 0 : 1);
        while (true) {
            pointer0 = 0;
            count = (number / 2) - 1;
            if (!position) {
                FirstBuffer = new Integer[length + length % 2][number];
                NewBuffer = FirstBuffer;
                OldBuffer = ZeroBuffer;
            } else {
                ZeroBuffer = new Integer[length + length % 2][number];
                NewBuffer = ZeroBuffer;
                OldBuffer = FirstBuffer;
            }
            for (int i = 0; i < length; i++) {
                pointer = 0;
                pointer1 = 0;
                NewPointer = pointer0 + 1;
                if (length == 1) {
                    for (int g = 0; g < size; g++) {
                        if (pointer > count || OldBuffer[pointer0][pointer] == null) {
                            array[g] = OldBuffer[NewPointer][pointer1];
                            pointer1++;
                        } else if (pointer1 > count || OldBuffer[NewPointer][pointer1] == null) {
                            if (OldBuffer[pointer0][pointer] == null) {
                                continue;
                            }
                            array[g] = OldBuffer[pointer0][pointer];
                            pointer++;
                        } else if (OldBuffer[pointer0][pointer] >= OldBuffer[NewPointer][pointer1]) {
                            array[g] = OldBuffer[NewPointer][pointer1];
                            pointer1++;
                        } else {
                            array[g] = OldBuffer[pointer0][pointer];
                            pointer++;
                        }
                    }
                    return;
                }
                for (int g = 0; g < number; g++) {
                    if (pointer > count || OldBuffer[pointer0][pointer] == null) {
                        if (OldBuffer[NewPointer][pointer1] == null) {
                            continue;
                        }
                        NewBuffer[i][g] = OldBuffer[NewPointer][pointer1];
                        pointer1++;
                    } else if (pointer1 > count || OldBuffer[NewPointer][pointer1] == null) {
                        if (OldBuffer[pointer0][pointer] == null) {
                            continue;
                        }
                        NewBuffer[i][g] = OldBuffer[pointer0][pointer];
                        pointer++;
                    } else if (OldBuffer[pointer0][pointer] >= OldBuffer[NewPointer][pointer1]) {
                        NewBuffer[i][g] = OldBuffer[NewPointer][pointer1];
                        pointer1++;
                    } else {
                        NewBuffer[i][g] = OldBuffer[pointer0][pointer];
                        pointer++;
                    }
                }
                pointer0 += 2;
            }
            position = !position;
            length = length / 2 + (length % 2 == 0 ? 0 : 1);
            number *= 2;

        }
    }

    public static void ShellSort(int[] array) {
        int j;
        for (int gap = array.length / 2; gap > 0; gap /= 2) {
            for (int i = gap; i < array.length; i++) {
                int temp = array[i];
                for (j = i; j >= gap && array[j - gap] > temp; j -= gap) {
                    array[j] = array[j - gap];
                }
                array[j] = temp;
            }
        }
    }

    private static void HeapSort(int[] array) {
        for (int i = array.length / 2 - 1; i >= 0; i--)
            shiftDown(array, i, array.length);
        for (int i = array.length - 1; i > 0; i--) {
            swap(array, 0, i);
            shiftDown(array, 0, i);
        }
    }

    private static void shiftDown(int[] array, int i, int n) {
        int child;
        int tmp;
        for (tmp = array[i]; leftChild(i) < n; i = child) {
            child = leftChild(i);
            if (child != n - 1 && (array[child] < array[child + 1]))
                child++;
            if (tmp < array[child])
                array[i] = array[child];
            else
                break;
        }
        array[i] = tmp;
    }

    private static int leftChild(int i) {
        return 2 * i + 1;
    }

    private static void swap(int[] array, int i, int j) {
        int temp = array[i];
        array[i] = array[j];
        array[j] = temp;
    }

    private static void MergeSort(int[] array, int low, int high) {
        if (low < high) {
            int mid = (low + high) / 2;
            MergeSort(array, low, mid);
            MergeSort(array, mid + 1, high);
            merge(array, low, mid, high);
        }
    }

    private static void merge(int[] array, int low, int mid, int high) {
        int n = high - low + 1;
        int[] Temp = new int[n];
        int i = low, j = mid + 1;
        int k = 0;
        while (i <= mid || j <= high) {
            if (i > mid)
                Temp[k++] = array[j++];
            else if (j > high)
                Temp[k++] = array[i++];
            else if (array[i] < array[j])
                Temp[k++] = array[i++];
            else
                Temp[k++] = array[j++];
        }
        for (j = 0; j < n; j++)
            array[low + j] = Temp[j];
    }

    private static void insertionSort(int[] elements) {
        for (int i = 1; i < elements.length; i++) {
            int key = elements[i];
            int j = i - 1;
            while (j >= 0 && key < elements[j]) {
                elements[j + 1] = elements[j];
                j--;
            }
            elements[j + 1] = key;
        }
    }
}

class Input {

    public BufferedReader read;
    public static boolean FileInput = false;

    Input() {
        try {
            read = new BufferedReader(FileInput ? new FileReader("input.txt") : new InputStreamReader(System.in));
        } catch (Exception error) {
        }
    }

    public int ReadInt() throws Exception {
        return Integer.parseInt(read.readLine());
    }

    public long ReadLong() throws Exception {
        return Long.parseLong(read.readLine());
    }

    public String ReadString() throws Exception {
        return read.readLine();
    }

    public int[] ReadArrayInt(String split) throws Exception {
        return Arrays.stream(read.readLine().split(split)).mapToInt(Integer::parseInt).toArray();
    }

    public long[] ReadArrayLong(String split) throws Exception {
        return Arrays.stream(read.readLine().split(split)).mapToLong(Long::parseLong).toArray();
    }

    public String[] ReadArrayString(String split) throws Exception {
        return read.readLine().split(split);
    }
}

class Output {

    public BufferedWriter write;
    public static boolean FileOutput = false;

    Output() {
        try {
            write = new BufferedWriter(FileOutput ? new FileWriter("output.txt") : new OutputStreamWriter(System.out));
        } catch (Exception error) {
        }
    }

    public void WriteArray(int[] array, String split) {
        try {
            int length = array.length;
            for (int index = 0; index < length; index++) {
                write.write(Integer.toString(array[index]));
                if (index + 1 != length) {
                    write.write(split);
                }
            }
        } catch (Exception error) {
        }


    }

    public void WriteArray(long[] array, String split) {
        try {
            int length = array.length;
            for (int index = 0; index < length; index++) {
                write.write(Long.toString(array[index]));
                if (index + 1 != length) {
                    write.write(split);
                }
            }
        } catch (Exception error) {
        }
    }

    public void WriteArray(String[] array, String split) {
        try {
            int length = array.length;
            for (int index = 0; index < length; index++) {
                write.write(array[index]);
                if (index + 1 != length) {
                    write.write(split);
                }
            }
        } catch (Exception error) {
        }
    }

    public void WriteArray(boolean[] array, String split) {
        try {
            int length = array.length;
            for (int index = 0; index < length; index++) {
                write.write(Boolean.toString(array[index]));
                if (index + 1 != length) {
                    write.write(split);
                }
            }
        } catch (Exception error) {
        }
    }

    public void WriteInt(int number, String split) {
        try {
            write.write(Integer.toString(number));
            write.write(split);
        } catch (Exception error) {
        }
    }

    public void WriteString(String word, String split) {
        try {
            write.write(word);
            write.write(split);
        } catch (Exception error) {
        }
    }

    public void WriteLong(Long number, String split) {
        try {
            write.write(Long.toString(number));
            write.write(split);
        } catch (Exception error) {
        }
    }

    public void WriteEnter() {
        try {
            write.newLine();
        } catch (Exception e) {
        }
    }
}