You are given two strings A and B representing essays of two students who are suspected cheaters. For any two strings C, D we define their similarity score S(C,D) as 4⋅ LCS(C,D) - |C| - |D|, where LCS(C,D) denotes the length of the Longest Common Subsequence of strings C and D. 

You believe that only some part of the essays could have been copied, therefore you're interested in their substrings.

Calculate the maximal similarity score over all pairs of substrings. More formally, output maximal S(C, D) over all pairs (C, D), where C is some substring of A, and D is some substring of B. 

If X is a string, |X| denotes its length.

A string a is a substring of a string b if a can be obtained from b by deletion of several (possibly, zero or all) characters from the beginning and several (possibly, zero or all) characters from the end.

A string a is a subsequence of a string b if a can be obtained from b by deletion of several (possibly, zero or all) characters. 

Pay attention to the difference between the substring and subsequence, as they both appear in the problem statement. 

You may wish to read the [Wikipedia page about the Longest Common Subsequence problem](https://en.wikipedia.org/wiki/Longest_common_subsequence_problem).

Input

The first line contains two positive integers n and m (1 ≤ n, m ≤ 5000) — lengths of the two strings A and B. 

The second line contains a string consisting of n lowercase Latin letters — string A.

The third line contains a string consisting of m lowercase Latin letters — string B. 

Output

Output maximal S(C, D) over all pairs (C, D), where C is some substring of A, and D is some substring of B. 

Examples

Input


4 5
abba
babab


Output


5

Input


8 10
bbbbabab
bbbabaaaaa


Output


12

Input


7 7
uiibwws
qhtkxcn


Output


0

Note

For the first case:

abb from the first string and abab from the second string have LCS equal to abb.

The result is S(abb, abab) = (4 ⋅ |abb|) - |abb| - |abab| = 4 ⋅ 3 - 3 - 4 = 5.
import java.io.*;
import java.util.*;
import java.math.*;
import java.lang.*;

public class Main implements Runnable {
    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;
        private BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1)
                throw new InputMismatchException();

            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }

                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }

        public int nextInt() {
            int c = read();

            while (isSpaceChar(c))
                c = read();

            int sgn = 1;

            if (c == '-') {
                sgn = -1;
                c = read();
            }

            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));

            return res * sgn;
        }

        public long nextLong() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;

            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public double nextDouble() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            double res = 0;
            while (!isSpaceChar(c) && c != '.') {
                if (c == 'e' || c == 'E')
                    return res * Math.pow(10, nextInt());
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            if (c == '.') {
                c = read();
                double m = 1;
                while (!isSpaceChar(c)) {
                    if (c == 'e' || c == 'E')
                        return res * Math.pow(10, nextInt());
                    if (c < '0' || c > '9')
                        throw new InputMismatchException();
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            return res * sgn;
        }

        public String readString() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isSpaceChar(c));

            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public String next() {
            return readString();
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);
        }
    }

    public static void main(String args[]) throws Exception {
        new Thread(null, new Main(), "Main", 1 << 27).start();
    }

    static class Pair {
        int f;
        int s;
        PrintWriter w;

        // int t;

        Pair(int f, int s) {
            // Pair(int f,int s, PrintWriter w){
            this.f = f;
            this.s = s;
            // this.w = w;
            // this.t = t;

        }

        public static Comparator<Pair> wc = new Comparator<Pair>() {
            public int compare(Pair e1, Pair e2) {

                // 1 for swap
                if (Math.abs(e1.f) - Math.abs(e2.f) != 0) {
                    // e1.w.println("**"+e1.f+" "+e2.f);
                    return (Math.abs(e1.f) - Math.abs(e2.f));
                } else {
                    // e1.w.println("##"+e1.f+" "+e2.f);
                    return (Math.abs(e1.s) - Math.abs(e2.s));
                }

            }
        };
    }

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

    //// recursive BFS
    public static int bfsr(int s, ArrayList<Integer>[] a, boolean[] b, int[] pre) {
        b[s] = true;
        int p = 1;
        int n = pre.length - 1;
        int t = a[s].size();
        int max = 1;
        for (int i = 0; i < t; i++) {
            int x = a[s].get(i);
            if (!b[x]) {
                // dist[x] = dist[s] + 1;
                int xz = (bfsr(x, a, b, pre));
                p += xz;
                max = Math.max(xz, max);
            }
        }
        // max = Math.max(max,(n-p));
        pre[s] = max;
        return p;
    }

    //// iterative BFS
    public static int bfs(int s, ArrayList<Integer>[] a, int dist, boolean[] b, PrintWriter w) {
        b[s] = true;
        int siz = 0;
        dist--;
        Queue<Integer> q = new LinkedList<>();
        q.add(s);
        while (q.size() != 0 && dist > 0) {
            int i = q.poll();
            Iterator<Integer> it = a[i].listIterator();
            int z = 0;
            while (it.hasNext() && dist > 0) {
                z = it.next();
                if (!b[z]) {
                    b[z] = true;
                    dist--;
                    // dist[z] = dist[i] + 1;
                    siz++;
                    q.add(z);
                }
            }

        }
        return siz;
    }

    public static int lower(int key, Integer[] a) {
        int l = 0;
        int r = a.length - 1;
        int res = 0;

        while (l <= r) {
            int mid = (l + r) / 2;

            if (a[mid] <= key) {
                l = mid + 1;
                res = mid + 1;
            } else {
                r = mid - 1;
            }
        }

        return res;
    }

    //////////////////////////////////////////////////////////////////////////////////////////////////////
    //////////////////////////////////////////////////////////////////////////////////////////////////////

    public void run() {
        // code here
        InputReader sc = new InputReader(System.in);
        PrintWriter w = new PrintWriter(System.out);

        int defaultValue = 0;
        long mod = Long.valueOf("1000000007");

        // int tc = sc.nextInt();
        // while (tc-- > 0) {

        int n = sc.nextInt();
        int m = sc.nextInt();
        String s1 = sc.next();
        String s2 = sc.next();
        int ans = 0;
        int[][] dp = new int[n + 1][m + 1];
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= m; j++) {
                char a = s1.charAt(i - 1);
                char b = s2.charAt(j - 1);

                if (a == b) {
                    dp[i][j] = Math.max(dp[i][j], dp[i - 1][j - 1] + 2);
                } else {
                    dp[i][j] = Math.max(0, Math.max(dp[i][j - 1] - 1, dp[i - 1][j] - 1));
                }

                ans = Math.max(ans, dp[i][j]);
            }
        }
        w.println(ans);

        // }
        w.flush();
        w.close();

    }

}
