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.util.stream.Collectors;

public class D_cheater {

    public static void main(String[] args) throws Exception {

        FastScanner sc = new FastScanner();
        FastWriter writer = new FastWriter();
        long start = System.currentTimeMillis();
        int n = sc.nextInt(), m = sc.nextInt();
        char a[] = sc.next().toCharArray();
        char b[] = sc.next().toCharArray();

        int dp[][] = new int[n+1][m+1];
        for(int i=0; i<=n; i++)
            Arrays.fill(dp[i], -2);
        dp[0][0] = 0;
        for(int i=0; i<n; i++)
            dp[i+1][0] = -1;

        for(int j=0; j<m; j++)
            dp[0][j+1] = -1;

        for(int i=0; i<n; i++)
            for(int j=0; j<m; j++) {

                if(a[i] == b[j])
                    dp[i+1][j+1] = max(dp[i+1][j+1], dp[i][j] + 2, 2);

                else {
                    dp[i+1][j+1] = max(dp[i+1][j+1], dp[i][j+1] - 1, dp[i+1][j] - 1);
                }
            }
        int ans = 0;
        for(int i=1; i<=n; i++)
            for(int j=1; j<=m; j++)
                ans = max(ans, dp[i][j]);
        println(ans);
    }

    static final Random random = new Random();

    static class FastScanner {
        private InputStream sin = System.in;
        private final byte[] buffer = new byte[1024];
        private int ptr = 0;
        private int buflen = 0;
        public FastScanner(){}
        public FastScanner(String filename) throws FileNotFoundException {
            File file = new File(filename);
            sin = new FileInputStream(file);
        }
        private boolean hasNextByte() {
            if (ptr < buflen) {
                return true;
            }else{
                ptr = 0;
                try {
                    buflen = sin.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 static 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) || 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());}
        public long[] nextLongArray(final int n){
            final long[] a = new long[n];
            for (int i = 0; i < n; i++)
                a[i] = nextLong();
            return a;
        }
        public int[] nextIntArray(final int n){
            final int[] a = new int[n];
            for (int i = 0; i < n; i++)
                a[i] = nextInt();
            return a;
        }
        public double[] nextDoubleArray(final int n){
            final double[] a = new double[n];
            for (int i = 0; i < n; i++)
                a[i] = nextDouble();
            return a;
        }

        public List<Integer>[] adjacencyList(int nodes, int edges) {
            return adjacencyList(nodes, edges, false);
        }
        public List<Integer>[] adjacencyList(int nodes, int edges, boolean isDirected) {

            List<Integer>[] adj = new ArrayList[nodes + 1];
            Arrays.setAll(adj, (i) -> new ArrayList<>());
            for (int i = 0; i < edges; i++) {
                int a = nextInt(), b = nextInt();
                adj[a].add(b);
                if (!isDirected) adj[b].add(a);
            }
            return adj;
        }
    }

    static class FastWriter {

        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(System.out));
        void print(int n) throws Exception { writer.write(n + ""); }
        void println(int n) throws Exception { writer.write(n + "\n"); }

        void print(long n) throws Exception { writer.write(n + ""); }
        void println(long n) throws Exception { writer.write(n + "\n"); }

        void print(String s) throws Exception { writer.write(s); }
        void println(String s) throws Exception { writer.write(s); writer.newLine(); }

        void println(int ar[]) throws Exception { for(int e : ar) writer.write(e + " "); writer.newLine(); }
        void println(long ar[]) throws Exception { for(long e : ar) writer.write(e + " "); writer.newLine(); }
        void println(double ar[]) throws Exception { for(double e : ar) writer.write(e + " "); writer.newLine(); }
        void close() throws Exception { writer.close(); }
        <T> void println(List<T> L) throws Exception { for(T o : L) writer.write(o + " "); writer.newLine(); }
    }

    static int findDistance(List<Integer> G[], int nodes, int src, int dst) {

        LinkedList<Integer> queue = new LinkedList<>();
        int dist[] = new int[nodes + 1];
        int ans = -1;
        dist[src] = 0;
        queue.add(src);
        while(queue.size() > 0) {
            int u = queue.poll();
            if(u == dst) {
                ans = dist[u];
            }
            for(int v : G[u]) {
                if(dist[v] >= 0)
                    continue;
                queue.add(v);
                dist[v] = dist[u] + 1;
            }
        }
        return ans;
    }

    static void sort(List<Integer> A) {
        shuffleList(A);
        Collections.sort(A);
    }

    static void shuffleList(List<Integer> A) {
        int n = A.size();
        for(int i = 0; i < n; i++) {
            int tmp = A.get(i);
            int randomPos = i + random.nextInt(n-i);
            A.set(i, A.get(randomPos));
            A.set(randomPos, tmp);
        }
    }

    static void sort(int A[]) {
        shuffleArray(A);
        Arrays.sort(A);
    }
    static void sort(long A[]) {
        shuffleArray(A);
        Arrays.sort(A);
    }
    static void sort(double A[]) {
        shuffleArray(A);
        Arrays.sort(A);
    }
    static <T> void sort(T[] A) {
        shuffleArray(A);
        Arrays.sort(A);
    }
    static <T> void shuffleArray(T[] A) {
        int n = A.length;
        for(int i = 0; i < n; i++) {
            T tmp = A[i];
            int randomPos = i + random.nextInt(n-i);
            A[i] = A[randomPos];
            A[randomPos] = tmp;
        }
    }
    static void shuffleArray(int[] A) {
        int n = A.length;
        for(int i = 0; i < n; i++) {
            int tmp = A[i];
            int randomPos = i + random.nextInt(n-i);
            A[i] = A[randomPos];
            A[randomPos] = tmp;
        }
    }
    static void shuffleArray(long[] A) {
        int n = A.length;
        for(int i = 0; i < n; i++) {
            long tmp = A[i];
            int randomPos = i + random.nextInt(n-i);
            A[i] = A[randomPos];
            A[randomPos] = tmp;
        }
    }
    static void shuffleArray(double[] A) {
        int n = A.length;
        for(int i = 0; i < n; i++) {
            double tmp = A[i];
            int randomPos = i + random.nextInt(n-i);
            A[i] = A[randomPos];
            A[randomPos] = tmp;
        }
    }

    static int[] subArray(int A[], int x, int y) {
        int B[] = new int[y - x + 1];
        for(int i = x; i <= y; i++)
            B[i-x] = A[i];
        return B;
    }

    static int[] toArray(List<Integer> L) {
        return L.stream().mapToInt(x -> x).toArray();
    }

    static void println(int[] A) {
        for(int e: A) System.out.print(e + " ");
        System.out.println();
    }

    static void println(long[] A) {
        for(long e: A) System.out.print(e + " ");
        System.out.println();
    }

    static void println(List arr) {
        for(Object e: arr) System.out.print(e + " ");
        System.out.println();
    }

    static <T> void println(T A[]) {

        for(T i : A)
            System.out.print(i + " ");
        System.out.println();
    }

    static void print(String s) {
        System.out.print(s);
    }
    static void println(long n) {
        System.out.println(n);
    }

    static void println(String s) {
        System.out.println(s);
    }

    static List<Integer> toList(int ar[]) {
        return Arrays.stream(ar).boxed().collect(Collectors.toList());
    }

    static List<Long> toList(long ar[]) {
        return Arrays.stream(ar).boxed().collect(Collectors.toList());
    }

    static List<Double> toList(double ar[]) {
        return Arrays.stream(ar).boxed().collect(Collectors.toList());
    }

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

    private static int abs(int a){  return (a>=0) ? a: -a;  }
    private static int min(int... ins){ return Arrays.stream(ins).min().getAsInt(); }
    private static int max(int... ins){ int max = ins[0]; for(int x : ins) max = Math.max(max, x); return max; }
    private static int sum(int... ins){ return Arrays.stream(ins).sum(); }
    private static long abs(long a){ return (a>=0) ? a: -a; }
    private static long min(long... ins){ return Arrays.stream(ins).min().getAsLong(); }
    private static long max(long... ins){ return Arrays.stream(ins).max().getAsLong(); }
    private static long sum(long... ins){ return Arrays.stream(ins).sum(); }
    private static double abs(double a){ return (a>=0) ? a: -a; }
    private static double min(double... ins){ return Arrays.stream(ins).min().getAsDouble(); }
    private static double max(double... ins){ return Arrays.stream(ins).max().getAsDouble(); }
    private static double sum(double... ins){ return Arrays.stream(ins).sum(); }

    private static class Pair implements Comparable<Pair> {
        int x, y;
        Pair(int x, int y) { this.x = x; this.y = y; }
        Pair() {}

        @Override
        public int compareTo(Pair other) {
            return x == other.x ? y - other.y : x - other.x;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
            Pair pair = (Pair) o;
            return x == pair.x &&
                    y == pair.y;
        }

        @Override
        public int hashCode() {
            return Objects.hash(x, y);
        }

        @Override
        public String toString() {
            return String.format("(%d, %d)", x, y);
        }
    }

    static int pow(long n, int p, int mod) {
        if(p == 0)
            return 1;
        long x = pow(n, p/2, mod);
        x = x * x % mod;
        return (int) ( p % 2 == 0 ? x : x * n % mod );
    }

    static long inv(int x, int m) {
        return pow(x, m - 2, m);
    }

    static int lowerBound(int ar[], int L, int R, int val) {
        if(val < ar[L] || val > ar[R])
            return -1;
        while(L <= R) {
            int mid = (L + R) / 2;
            if(ar[mid] >= val)
                R = mid - 1;
            else
                L = mid + 1;
        }
        return ar[L] == val ? L : -1;
    }

    static int upperBound(int ar[], int L, int R, int val) {
        if(val < ar[L] || val > ar[R])
            return -1;
        while(L <= R) {
            int mid = (L + R) / 2;
            if(ar[mid] > val)
                R = mid - 1;
            else
                L = mid + 1;
        }
        return ar[R] == val ? R : -1;
    }
}

