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.*;

public class TP {

    // constants
    static final int MOD = (int) (1e9 + 7);
    static final int IMAX = 0x7fffffff;
    static final int IMIN = 0x80000000;
    static final long LMAX = 0x7fffffffffffffffL;
    static final long LMIN = -0x8000000000000000L;
    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")));
        pre();
        int t = 1;
//        t = ni();
        while (t-- > 0)
            solve();
        out.flush();
        tr(System.currentTimeMillis() - s + "ms");
    }

    private static void pre() {

    }

    private static void solve() {

        int n = ni(), m = ni();
        char[] a = ns().toCharArray();
        char[] b = ns().toCharArray();
        int[][] dp = new int[n + 1][m + 1];
        int max = 0;
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= m; j++) {
                if (a[i - 1] == b[j - 1])
                    dp[i][j] = max(dp[i][j], dp[i - 1][j - 1] + 2);
                else
                    dp[i][j] = max(dp[i][j], dp[i - 1][j]-1, dp[i][j - 1]-1);
                max = max(max, dp[i][j]);
            }
        }
        out.println(max);
    }

    //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();
    }

    // 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 min(int... x) {
        if (x.length == 1) return x[0];
        if (x.length == 2) return Math.min(x[0], x[1]);
        if (x.length == 3) return Math.min(x[0], Math.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 min(long... x) {
        if (x.length == 1) return x[0];
        if (x.length == 2) return Math.min(x[0], x[1]);
        if (x.length == 3) return Math.min(x[0], Math.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 max(int... x) {
        if (x.length == 1) return x[0];
        if (x.length == 2) return Math.max(x[0], x[1]);
        if (x.length == 3) return Math.max(x[0], Math.max(x[1], x[2]));
        return Arrays.stream(x).max().getAsInt();
    }

    static long max(long... x) {
        if (x.length == 1) return x[0];
        if (x.length == 2) return Math.max(x[0], x[1]);
        if (x.length == 3) return Math.max(x[0], Math.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 pow(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 pow(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 int power(int x, int y, int p) {
        int res = 1;
        x = x % p;
        while (y > 0) {
            if (y % 2 == 1)
                res = (res * x) % p;
            y = y >> 1;
            x = (x * x) % p;
        }
        return res;
    }

    static int modInverse(int n, int p) {
        return power(n, p - 2, p);
    }

    static int nCrModPFermat(int n, int r, int p) {
        if (n < r)
            return 0;
        if (r == 0)
            return 1;
        int[] fac = new int[n + 1];
        fac[0] = 1;
        for (int i = 1; i <= n; i++)
            fac[i] = fac[i - 1] * i % p;
        return (fac[n] * modInverse(fac[r], p) % p * modInverse(fac[n - r], p) % p) % p;
    }

    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};
    }

    public static int[] enumPrimes(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 Arrays.copyOf(primes, tot);
    }

    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());
        }
    }

}