Vasya plays the LionAge II. He was bored of playing with a stupid computer, so he installed this popular MMORPG, to fight with his friends. Vasya came up with the name of his character — non-empty string s, consisting of a lowercase Latin letters. However, in order not to put up a front of friends, Vasya has decided to change no more than k letters of the character name so that the new name sounded as good as possible. Euphony of the line is defined as follows: for each pair of adjacent letters x and y (x immediately precedes y) the bonus c(x, y) is added to the result. Your task is to determine what the greatest Euphony can be obtained by changing at most k letters in the name of the Vasya's character.

Input

The first line contains character's name s and an integer number k (0 ≤ k ≤ 100). The length of the nonempty string s does not exceed 100. The second line contains an integer number n (0 ≤ n ≤ 676) — amount of pairs of letters, giving bonus to the euphony. The next n lines contain description of these pairs «x y c», which means that sequence xy gives bonus c (x, y — lowercase Latin letters,  - 1000 ≤ c ≤ 1000). It is guaranteed that no pair x y mentioned twice in the input data.

Output

Output the only number — maximum possible euphony оf the new character's name.

Examples

Input

winner 4
4
s e 7
o s 8
l o 13
o o 8


Output

36

Input

abcdef 1
5
a b -10
b c 5
c d 5
d e 5
e f 5


Output

20

Note

In the first example the most euphony name will be looser. It is easy to calculate that its euphony is 36.
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.StringTokenizer;

/**
 * Created by Egor on 22/09/14.
 */
public class Task73C {

    BufferedReader reader;
    StringTokenizer tokenizer;
    PrintWriter writer;

    public String nextToken() throws IOException {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            tokenizer = new StringTokenizer(reader.readLine());
        }
        return tokenizer.nextToken();
    }

    public int nextInt() throws IOException {
        return Integer.parseInt(nextToken());
    }

    public double nextDouble() throws IOException {
        return Double.parseDouble(nextToken());
    }

    public long nextLong() throws IOException {
        return Long.parseLong(nextToken());
    }

    public char nextChar() throws IOException {
        return nextToken().charAt(0);
    }

    public static void main(String[] args) throws IOException {
        new Task73C().run();
    }

    public static final int INFINITY = 999999;

    public void solve() throws IOException {
        String s = nextToken();
        char[] c = s.toCharArray();
        int k = nextInt();
        int[][] changes = new int[123][123];
        int n = nextInt();
        for (int i = 0; i < n; i++) {
            char first = nextChar();
            char second = nextChar();
            changes[first][second] = nextInt();
        }

        int[][][] d = new int[c.length][k + 1][123];
        for (int[][] aD : d) {
            for (int[] anAD : aD) {
                Arrays.fill(anAD, -INFINITY);
            }
        }

//        System.out.println((int)'a' + " : " + (int) 'z');
        if (k != 0) {
            for (int i = 97; i <= 122; i++) {

                d[0][i == c[0] ? 0 : 1][i] = 0;
            }
        } else {
            d[0][0][c[0]] = 0;
        }

        for (int i = 1; i < c.length; i++) {
            d[i][0][c[i]] = d[i - 1][0][c[i - 1]] + changes[c[i - 1]][c[i]];
            for (int j = 1; j <= k; j++) {
                for (int q = 97; q <= 122; q++) {
                    int prevJ = q == c[i] ? j : j - 1;
//                    int prevJ = j - 1;
                    for (int l = 97; l <= 122; l++) {
                        if (d[i - 1][prevJ][l] != -INFINITY) {
                            d[i][j][q] = Math.max(d[i][j][q], d[i - 1][prevJ][l] + changes[l][q]);
                        }
                    }
                }
            }
        }
        int answer = -INFINITY;
        for (int i = 0; i <= k; i++) {
            answer = Math.max(answer, max(d[c.length - 1][i]));
        }

//        StringBuilder builder = new StringBuilder();
//        for (int i = 0; i <= c.length - 1; i++) {
//            for (int q = 0; q <= k; q++) {
//                for (int asd = 97; asd <= 122; asd++) {
//                    builder.append(d[i][q][asd]).append(" ");
//                }
//                builder.append("\n");
//            }
//            builder.append("\n");
//        }
//        System.out.println(builder.toString());

        writer.println(answer);
    }

    public int max(int[] x) {
        int result = -INFINITY;
        for (int a : x) {
            result = Math.max(result, a);
        }
        return result;
    }

    public void run() {
        try {
            reader = new BufferedReader(new InputStreamReader(System.in));
            writer = new PrintWriter(System.out);

            solve();

            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
            System.exit(1);
        }
    }

}
