You are given two strings s and t consisting of lowercase Latin letters. The length of t is 2 (i.e. this string consists only of two characters).

In one move, you can choose any character of s and replace it with any lowercase Latin letter. More formally, you choose some i and replace s_i (the character at the position i) with some character from 'a' to 'z'.

You want to do no more than k replacements in such a way that maximizes the number of occurrences of t in s as a subsequence.

Recall that a subsequence is a sequence that can be derived from the given sequence by deleting zero or more elements without changing the order of the remaining elements.

Input

The first line of the input contains two integers n and k (2 ≤ n ≤ 200; 0 ≤ k ≤ n) — the length of s and the maximum number of moves you can make. The second line of the input contains the string s consisting of n lowercase Latin letters. The third line of the input contains the string t consisting of two lowercase Latin letters.

Output

Print one integer — the maximum possible number of occurrences of t in s as a subsequence if you replace no more than k characters in s optimally.

Examples

Input


4 2
bbaa
ab


Output


3


Input


7 3
asddsaf
sd


Output


10


Input


15 6
qwertyhgfdsazxc
qa


Output


16


Input


7 2
abacaba
aa


Output


15

Note

In the first example, you can obtain the string "abab" replacing s_1 with 'a' and s_4 with 'b'. Then the answer is 3.

In the second example, you can obtain the string "ssddsdd" and get the answer 10.

In the fourth example, you can obtain the string "aaacaaa" and get the answer 15.
/*
    Java might be good for Competitive Programming but Python still rocks!!!!!!!!!


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                         ppppp  ppppppppppppppppppp
                      ppppppp    ppppppppppppppppppppp
                      pppppppp  pppppppppppppppppppppp
                      pppppppppppppppppppppppppppppppp
                              pppppppppppppppppppppppp
       ppppppppppppppppppppppppppppppppppppppppppppppp  pppppppppppppppppppp
      pppppppppppppppppppppppppppppppppppppppppppppppp  ppppppppppppppppppppp
     ppppppppppppppppppppppppppppppppppppppppppppppppp  pppppppppppppppppppppp
    ppppppppppppppppppppppppppppppppppppppppppppppp    pppppppppppppppppppppppp
   pppppppppppppppppppppppppppppppppppppppppppppp     pppppppppppppppppppppppppp
  ppppppppppppppppppppppppppppppppppppppppppppp      pppppppppppppppppppppppppppp
  pppppppppppppppppppppppppppppppp               pppppppppppppppppppppppppppppppp
  pppppppppppppppppppppppppppp     pppppppppppppppppppppppppppppppppppppppppppppp
  ppppppppppppppppppppppppppp    pppppppppppppppppppppppppppppppppppppppppppppppp
    pppppppppppppppppppppppp  pppppppppppppppppppppppppppppppppppppppppppppppppp
     ppppppppppppppppppppppp  ppppppppppppppppppppppppppppppppppppppppppppppppp
      pppppppppppppppppppppp  ppppppppppppppppppppppppppppppppppppppppppppppp
       ppppppppppppppppppppp  ppppppppppppppppppppppppppppppppppppppppppppp
                              pppppppppppppppppppppppp
                              pppppppppppppppppppppppppppppppp
                              pppppppppppppppppppppp  pppppppp
                              ppppppppppppppppppppp    ppppppp
                                 ppppppppppppppppppp  ppppp
                                    pppppppppppppppppppp
*/


import java.util.*;
import java.lang.*;
import java.io.*;
public final class ProblemF
{
    public static BufferedWriter out = new BufferedWriter(new OutputStreamWriter(System.out));
    public static int n, i, j, k, u, v;
    public static String s, t;
    public static char a, b;
    public static int[][][] dp = new int[201][201][201];
    public static void main(String[] args) throws IOException
    {
        FastScanner sc = new FastScanner();
        Print print = new Print();
        n = sc.nextInt();
        k = sc.nextInt();
        s = sc.next();
        t = sc.next();
        a = t.charAt(0);
        b = t.charAt(1);
        for(i = 0; i <= 200; i++)
            for(j = 0; j <= 200; j++)
                Arrays.fill(dp[i][j], -1);
        print.integer(recur(0, 0, 0));
        out.close();
    }

    public static int recur(int i, int j, int count)
    {
        if(i == n)
            return 0;
        if(dp[i][j][count] != -1)
            return dp[i][j][count];
        dp[i][j][count] = recur(i+1, j, count + (s.charAt(i) == a? 1: 0)) + (s.charAt(i) == b? count: 0);
        if(j < k && s.charAt(i) != a)
            dp[i][j][count] = Math.max(dp[i][j][count], recur(i+1, j+1, count+1) + (a == b ? count: 0));
        if(j < k && s.charAt(i) != b)
            dp[i][j][count] = Math.max(dp[i][j][count], recur(i+1, j+1, count) + count);
        return dp[i][j][count];
    }

    public static class Print
    {
        Print()
        {}

        void integer(int... arr) throws IOException
        {
            for(int value: arr)
            {
                out.write(value+" ");
                out.flush();
            }
            out.write("\n");
            out.flush();
        }

        void string(String... arr) throws IOException
        {
            for(String value: arr)
            {
                out.write(value+" ");
                out.flush();
            }
            out.write("\n");
            out.flush();
        }

        void character(char... arr) throws IOException
        {
            for(char value: arr)
            {
                out.write(value+" ");
                out.flush();
            }
            out.write("\n");
            out.flush();
        }

        void long_int(long... arr) throws IOException
        {
            for(long value: arr)
            {
                out.write(value+" ");
                out.flush();
            }
            out.write("\n");
            out.flush();
        }
    }

    static class FastScanner
    {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st=new StringTokenizer("");
        String next()
        {
            while (!st.hasMoreTokens())
                try
                {
                    st=new StringTokenizer(br.readLine());
                } catch (IOException e)
                {
                    e.printStackTrace();
                }
            return st.nextToken();
        }

        int nextInt()
        {
            return Integer.parseInt(next());
        }
        int[] readArray(int n)
        {
            int[] a=new int[n];
            for (int i=0; i<n; i++) a[i]=nextInt();
            return a;
        }
        long[] readLongArray(int n)
        {
            long[] a=new long[n];
            for (int i=0; i<n; i++) a[i]=nextLong();
            return a;
        }
        long nextLong()
        {
            return Long.parseLong(next());
        }
    }
}
