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.
import java.io.*;
import java.math.*;
import java.util.*;

import static java.lang.Math.*;
import static java.util.Arrays.*;

public class TP {

    public static PrintWriter out;
    public static FastReader in;


    public static void main(String[] args) throws IOException {
        long s = System.currentTimeMillis();
        in = new FastReader();
        out = new PrintWriter(System.out);
//        out = new PrintWriter(new BufferedWriter(new FileWriter("whereami.out")));
        int t = 1;
//        t = ni();
        while (t-- > 0) solve();
        out.flush();
        tr(System.currentTimeMillis() - s + "ms");
    }

    private static void solve() {
        int n =  ni();
        int[][] a = new int[n][2];
        for (int i = 0; i < 2 *n; i++) {
            int h = ni();
            if (a[h - 1][0] == 0)
                a[h - 1][0] = i+1;
            else a[h - 1][1] = i+1;
        }
        tr(a);
        long result = a[0][0] - 1 + a[0][1] - 1;
        for (int i = 0; i < n - 1; i++) {
            long s = a[i][0],
                    d = a[i][1],
                    A = a[i + 1][0],
                    B = a[i + 1][1];
            result += Math.min(Math.abs(s - A) + Math.abs(d - B), Math.abs(s - B) + Math.abs(d - A));
        }
        out.println(result);
    }


    //input
    private static int ni() {
        return in.nextInt();
    }

    private static String ns() {
        return in.next();
    }

    private static int[] na(int n) {
        int[] a = new int[n];
        for (int i = 0; i < n; i++) a[i] = ni();
        return a;
    }

    private static long[] nal(int n) {
        long[] a = new long[n];
        for (int i = 0; i < n; i++) a[i] = nl();
        return a;
    }

    private static long nl() {
        return in.nextLong();
    }

    private float nf() {
        return (float) in.nextDouble();
    }

    private static double nd() {
        return in.nextDouble();
    }

    private static void print(int[] a) {
        for (int x : a) out.print(x + " ");
        out.println();
    }

    private static void print(long[] a) {
        for (long x : a) out.print(x + " ");
        out.println();
    }


    // constants
    static final int IBIG = 1000000007;
    static final int IMAX = 0x7fffffff;
    static final int IMIN = 0x80000000;
    static final long LMAX = 0x7fffffffffffffffL;
    static final long LMIN = -0x8000000000000000L;

    // array util
    static void reverse(int[] a) {
        for (int i = 0, n = a.length, half = n / 2; i < half; ++i) {
            int swap = a[i];
            a[i] = a[n - i - 1];
            a[n - i - 1] = swap;
        }
    }

    static void reverse(long[] a) {
        for (int i = 0, n = a.length, half = n / 2; i < half; ++i) {
            long swap = a[i];
            a[i] = a[n - i - 1];
            a[n - i - 1] = swap;
        }
    }

    static void reverse(char[] a) {
        for (int i = 0, n = a.length, half = n / 2; i < half; ++i) {
            char swap = a[i];
            a[i] = a[n - i - 1];
            a[n - i - 1] = swap;
        }
    }

    static int[] copy(int[] a) {
        int[] ans = new int[a.length];
        for (int i = 0; i < a.length; ++i) ans[i] = a[i];
        return ans;
    }

    static long[] copy(long[] a) {
        long[] ans = new long[a.length];
        for (int i = 0; i < a.length; ++i) ans[i] = a[i];
        return ans;
    }

    static char[] copy(char[] a) {
        char[] ans = new char[a.length];
        for (int i = 0; i < a.length; ++i) ans[i] = a[i];
        return ans;
    }


    // math util
    static int minof(int a, int b, int c) {
        return min(a, min(b, c));
    }

    static int minof(int... x) {
        if (x.length == 1) return x[0];
        if (x.length == 2) return min(x[0], x[1]);
        if (x.length == 3) return min(x[0], min(x[1], x[2]));
        int min = x[0];
        for (int i = 1; i < x.length; ++i) if (x[i] < min) min = x[i];
        return min;
    }

    static long minof(long a, long b, long c) {
        return min(a, min(b, c));
    }

    static long minof(long... x) {
        if (x.length == 1) return x[0];
        if (x.length == 2) return min(x[0], x[1]);
        if (x.length == 3) return min(x[0], min(x[1], x[2]));
        long min = x[0];
        for (int i = 1; i < x.length; ++i) if (x[i] < min) min = x[i];
        return min;
    }

    static int maxof(int a, int b, int c) {
        return max(a, max(b, c));
    }

    static int maxof(int... x) {
        if (x.length == 1) return x[0];
        if (x.length == 2) return max(x[0], x[1]);
        if (x.length == 3) return max(x[0], max(x[1], x[2]));
        int max = x[0];
        for (int i = 1; i < x.length; ++i) if (x[i] > max) max = x[i];
        return max;
    }

    static long maxof(long a, long b, long c) {
        return max(a, max(b, c));
    }

    static long maxof(long... x) {
        if (x.length == 1) return x[0];
        if (x.length == 2) return max(x[0], x[1]);
        if (x.length == 3) return max(x[0], max(x[1], x[2]));
        long max = x[0];
        for (int i = 1; i < x.length; ++i) if (x[i] > max) max = x[i];
        return max;
    }

    static int powi(int a, int b) {
        if (a == 0) return 0;
        int ans = 1;
        while (b > 0) {
            if ((b & 1) > 0) ans *= a;
            a *= a;
            b >>= 1;
        }
        return ans;
    }

    static long powl(long a, int b) {
        if (a == 0) return 0;
        long ans = 1;
        while (b > 0) {
            if ((b & 1) > 0) ans *= a;
            a *= a;
            b >>= 1;
        }
        return ans;
    }

    static boolean isPrime(long n) {
        for (long i = 2; i * i <= n; i++) if (n % i == 0) return false;
        return true;
    }

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

    private static boolean sorted(int[] a) {
        for (int i = 0; i < a.length - 1; i++) {
            if (a[i] > a[i + 1]) return false;
        }
        return true;
    }

    private static boolean sorted(long[] a) {
        for (int i = 0; i < a.length - 1; i++) {
            if (a[i] > a[i + 1]) return false;
        }
        return true;
    }

    private static boolean sorted(char[] a) {
        for (int i = 0; i < a.length - 1; i++) {
            if (a[i] > a[i + 1]) return false;
        }
        return true;
    }

    public static int lowerBound(int[] a, int v) {
        int low = -1, high = a.length;
        while (high - low > 1) {
            int h = high + low >>> 1;
            if (a[h] >= v) {
                high = h;
            } else {
                low = h;
            }
        }
        return high;
    }

    public static int[] facs(int n, int[] primes) {
        int[] ret = new int[9];
        int rp = 0;
        for (int p : primes) {
            if (p * p > n) break;
            int i;
            i = 0;
            while (n % p == 0) {
                n /= p;
                i++;
            }
            if (i > 0) ret[rp++] = p;
        }
        if (n != 1) ret[rp++] = n;
        return Arrays.copyOf(ret, rp);
    }

    public static int[] sieveEratosthenes(int n) {
        if (n <= 32) {
            int[] primes = {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31};
            for (int i = 0; i < primes.length; i++) {
                if (n < primes[i]) {
                    return Arrays.copyOf(primes, i);
                }
            }
            return primes;
        }

        int u = n + 32;
        double lu = Math.log(u);
        int[] ret = new int[(int) (u / lu + u / lu / lu * 1.5)];
        ret[0] = 2;
        int pos = 1;

        int[] isnp = new int[(n + 1) / 32 / 2 + 1];
        int sup = (n + 1) / 32 / 2 + 1;

        int[] tprimes = {3, 5, 7, 11, 13, 17, 19, 23, 29, 31};
        for (int tp : tprimes) {
            ret[pos++] = tp;
            int[] ptn = new int[tp];
            for (int i = (tp - 3) / 2; i < tp << 5; i += tp) ptn[i >> 5] |= 1 << (i & 31);
            for (int j = 0; j < sup; j += tp) {
                for (int i = 0; i < tp && i + j < sup; i++) {
                    isnp[j + i] |= ptn[i];
                }
            }
        }

        // 3,5,7
        // 2x+3=n
        int[] magic = {
                0, 1, 23, 2, 29, 24, 19, 3, 30, 27, 25, 11, 20, 8, 4, 13, 31, 22, 28, 18, 26, 10, 7, 12, 21,
                17, 9, 6, 16, 5, 15, 14
        };
        int h = n / 2;
        for (int i = 0; i < sup; i++) {
            for (int j = ~isnp[i]; j != 0; j &= j - 1) {
                int pp = i << 5 | magic[(j & -j) * 0x076be629 >>> 27];
                int p = 2 * pp + 3;
                if (p > n) break;
                ret[pos++] = p;
                if ((long) p * p > n) continue;
                for (int q = (p * p - 3) / 2; q <= h; q += p) isnp[q >> 5] |= 1 << q;
            }
        }

        return Arrays.copyOf(ret, pos);
    }

    private static int[][] uniqCount(int[] a) {
        int n = a.length;
        int p = 0;
        int[][] b = new int[n][];
        for (int i = 0; i < n; i++) {
            if (i == 0 || a[i] != a[i - 1]) b[p++] = new int[]{a[i], 0};
            b[p - 1][1]++;
        }
        return Arrays.copyOf(b, p);
    }

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

    public static int[][] enumPrimesAndLPF(int n) {
        int[] lpf = new int[n + 1];
        double lu = Math.log(n + 32);

        int tot = 0;
        int[] primes = new int[(int) ((n + 32) / lu + (n + 32) / lu / lu * 1.5)];

        for (int i = 2; i <= n; i++) {
            lpf[i] = i;
        }

        for (int p = 2, tmp; p <= n; p++) {
            if (lpf[p] == p) {
                primes[tot++] = p;
            }
            for (int i = 0; i < tot && primes[i] <= lpf[p] && (tmp = primes[i] * p) <= n; i++) {
                lpf[tmp] = primes[i];
            }
        }

        return new int[][]{Arrays.copyOf(primes, tot), lpf};
    }

    static boolean isPrime(int n) {
        for (int i = 2; i * i <= n; i++) if (n % i == 0) return false;
        return true;
    }

    //debug
    private static final boolean oj = System.getProperty("ONLINE_JUDGE") != null;

    private static void tr(Object... o) {
        if (!oj) System.out.println(Arrays.deepToString(o));
    }

    //reader
    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() throws FileNotFoundException {
            br = new BufferedReader(new InputStreamReader(System.in));
//            br = new BufferedReader(new FileReader("whereami.in"));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }
    }

}
