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.math.BigDecimal;
import java.math.BigInteger;
import java.math.RoundingMode;
import java.util.*;
import java.util.concurrent.LinkedBlockingDeque;


public class scratch_25 {
    // int count=0;
    //static long count=0;
    static class Reader {
        static BufferedReader reader;
        static StringTokenizer tokenizer;

        /**
         * call this method to initialize reader for InputStream
         */
        static void init(InputStream input) {
            reader = new BufferedReader(
                    new InputStreamReader(input));
            tokenizer = new StringTokenizer("");
        }

        /**
         * get next word
         */
        static String next() throws IOException {
            while (!tokenizer.hasMoreTokens()) {
                //TODO add check for eof if necessary
                tokenizer = new StringTokenizer(
                        reader.readLine());
            }
            return tokenizer.nextToken();
        }

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

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

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





    static class Pair implements Comparable<Pair>{
        long x;
        long y;
        public Pair(long x,long y){
            this.x=x;
            this.y=y;
        }
        @Override
        public int compareTo(Pair o){
            return (int)this.y-(int)o.y;


        }
        @Override
        public boolean equals(Object me) {
            Pair binMe = (Pair)me;
            if(this.x==binMe.x && this.y==binMe.y)
                return true;
            else
                return false;
        }

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

        @Override
        public String toString() {
            return x+" "+y;
        }


    }






    public static void main(String[] args)  throws IOException {
        Reader.init(System.in);
        BufferedWriter out = new BufferedWriter(new OutputStreamWriter(System.out));
        int n1= Reader.nextInt();
        int n2= Reader.nextInt();
        String s1= Reader.next();
        String s2= Reader.next();
        System.out.println( lcs_iterative(s1,s2,n1,n2));



    }
    public static int lcs_iterative(String s1, String s2, int l1, int l2){
        int dp[][]= new int[l1+1][l2+1];
//        for (int i = 0; i <l1+1 ; i++) {
//            dp[i][0]=0;
//        }
//
//        for (int j = 0; j <l2+1 ; j++) {
//            dp[0][j]=0;
//        }

        for (int i = 1; i <l1+1 ; i++) {
            for (int j = 1; j <l2+1 ; j++) {
                if(s1.charAt(i-1)==s2.charAt(j-1)){
                    dp[i][j]= Math.max(dp[i][j],dp[i-1][j-1])+2;
                }
                else{
                    dp[i][j]= Math.max(dp[i][j-1], dp[i-1][j])-1;
                }
            }
        }
        int max=0;

        for (int i = 0; i <=l1 ; i++) {
            for (int j = 0; j <=l2 ; j++) {
                max= Math.max(max,dp[i][j]);
            }
        }
        return max;
    }



    public static void bfs(int x,int y, int n,char [][]ar,int done[][]){
        LinkedList<int[]>stk= new LinkedList<>();
        int a[]={x,y};
        stk.addFirst(a);
        while(!stk.isEmpty()){
            int b[]=stk.removeFirst();
            if(done[b[0]][b[1]]==1){
                continue;
            }
            done[b[0]][b[1]]=1;
            int arr[][]={{1,0},{-1,0},{0,1},{0,-1}};
            for (int i = 0; i <arr.length ; i++) {
                if(!(b[0]+arr[i][0]>=n || b[1]+arr[i][1]>=n || b[0]+arr[i][0]<0 || b[1]+arr[i][1]<0 ||  ar[b[0]+arr[i][0]][b[1]+arr[i][1]]=='1')){
                    int r[]= {b[0]+arr[i][0], b[1]+arr[i][1]};
                    stk.addFirst(r);
                    // continue;
                }
            }
        }
    }




























    public static ArrayList<Integer> Sieve(int n) {
        boolean arr[]= new boolean [n+1];
        Arrays.fill(arr,true);
        arr[0]=false;
        arr[1]=false;
        for (int i = 2; i*i <=n ; i++) {
            if(arr[i]){
                for (int j = 2; j <=n/i ; j++) {
                    int u= i*j;
                    arr[u]=false;
                }}
        }
        ArrayList<Integer> ans= new ArrayList<>();
        for (int i = 0; i <n+1 ; i++) {
            if(arr[i]){
                ans.add(i);
            }
        }
        return ans;
    }




    static long power( long x, long y, long p)
    {

        long res = 1;


        x = x % p;

        if (x == 0) return 0;

        while (y > 0)
        {

            if((y & 1)==1)
                res = (res * x) % p;


            y = y >> 1;
            x = (x * x) % p;
        }
        return res;
    }

    public static long ceil_div(long a, long b){
        return (a+b-1)/b;
    }

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

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

}