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.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.List;
import java.util.StringTokenizer;

public class Main {
	public static void main(String[] args) {
		InputReader in = new InputReader(System.in);
		PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)), true);
		TaskB solver = new TaskB();
		solver.solve(1, in, out);
		out.flush();
		out.close();
	}
}

class Pair<A, B> {
	A first;
	B second;

	Pair(A first, B second) {
		this.first = first;
		this.second = second;
	}

}

class TaskB {
	int INF = (int) 1e9 + 7;
	int MAX_N = (int) 1e5 + 5;
	long mod = (long) 1e8;
	List<Integer> ans;

	public void solve(int testNumber, InputReader in, PrintWriter pw) {
		char arr[] = in.next().toCharArray();
		int len = arr.length;
		int k = in.nextInt();
		int n = in.nextInt();
		int c[][] = new int[26][26];
		for (int i = 0; i < n; i++) {
			char a = in.next().charAt(0);
			char b = in.next().charAt(0);
			int cost = in.nextInt();
			c[a - 'a'][b - 'a'] = cost;
		}
		int dp[][][] = new int[len][26][105];
		// dp[i][j][k] stores the max euphony up till the ith index with j letters
		// changed and ending with k char
		for (int i = 0; i < len; i++) {
			for (int j = 0; j < 26; j++) {
				for (int l = 0; l <= k; l++) {
					dp[i][j][l] = -INF;
				}
			}
		}
		for (int i = 0; i < 26; i++) {
			if (arr[0] - 'a' == i) {
				dp[0][i][0] = 0;
			} else {
				dp[0][i][1] = 0;
			}
		}
		for (int i = 0; i < len - 1; i++) {
			for (int l = 0; l < 26; l++) {
				for (int j = 0; j <= k; j++) {
					if (dp[i][l][j] == -INF) {
						continue;
					}
					for (int r = 0; r < 26; r++) {
						if (arr[i + 1] - 'a' == r) {
							dp[i + 1][r][j] = Math.max(dp[i + 1][r][j], dp[i][l][j] + c[l][r]);
						} else {
							dp[i + 1][r][j + 1] = Math.max(dp[i + 1][r][j + 1], dp[i][l][j] + c[l][r]);
						}
					}
				}
			}
		}
		int ans = -INF;
		for (int i = 0; i <= k; i++) {
			for (int j = 0; j < 26; j++) {
				ans = Math.max(dp[len - 1][j][i], ans);
			}
		}
		pw.println(ans);

	}

	int[] shrink(int a[]) {
		int n = a.length;
		long b[] = new long[n];
		for (int i = 0; i < n; i++) {
			b[i] = ((long) (a[i] << 32)) | i;
		}
		Arrays.sort(b);
		int ret[] = new int[n];
		int p = 0;
		for (int i = 0; i < n; i++) {
			if (i > 0 && (b[i] ^ b[i - 1]) >> 32 != 0) {
				p++;
			}
			ret[(int) b[i]] = p;
		}
		return ret;
	}

	int sum(int ft[], int i) {
		int sum = 0;
		for (int j = i; j >= 1; j -= (j & -j)) {
			sum += ft[j];
//			System.out.println(sum);
		}
		return sum;
	}

	void add(int ft[], int i, int x) {
		for (int j = i; j < ft.length; j += (j & -j)) {
//			System.out.println(j);
			ft[j] += x;
		}
	}

	boolean isValid(int i, int j, char arr[][]) {

		if (i >= arr[0].length || j >= arr[0].length) {
			return false;
		}
		if (arr[i][j] == '*') {
			return false;
		}
		return true;
	}

	long pow(long m, long k) {
		long prod = 1;
		for (int i = 0; i < k; i++) {
			prod = (prod * m) % INF;
		}
		return prod % INF;
	}

//	int sum(int k) {
//		int sum=0;
//		for(int i=k;i>=1;i) {
//			sum+=ft[k];
//		}
//	}

	long fib(int N) {
		long fib[] = new long[N + 1];
		fib[0] = 1;
		fib[1] = 1;
		for (int i = 2; i <= N; i++) {
			fib[i] = (fib[i - 1] + fib[i - 2]) % mod;
		}
		return fib[N] % mod;
	}

	long sum(int i, int j, long arr[]) {
		long sum = 0;
		for (int k = i; k <= j; k++) {
			sum += arr[k];
		}
		return sum;
	}

	boolean FirstRow_Col(Pair<Integer, Integer> pair) {
		return pair.first == 0 || pair.second == 0;
	}

	int __gcd(int a, int b) {
		if (b == 0)
			return a;
		return __gcd(b, a % b);

	}

	public int getInt(int num) {
		int ret = -1;
		switch (num) {
		case 0:
			ret = 6;
			break;
		case 1:
			ret = 2;
			break;
		case 2:
			ret = 5;
			break;
		case 3:
			ret = 5;
			break;
		case 4:
			ret = 4;
			break;
		case 5:
			ret = 5;
			break;
		case 6:
			ret = 6;
			break;
		case 7:
			ret = 3;
			break;
		case 8:
			ret = 7;
			break;
		case 9:
			ret = 6;
			break;
		}
		return ret;
	}

	public int isPow(long num) {
		int count = 0;
		while (num > 0) {
			num /= 2;
			count++;
		}
		return count;
	}
}

class InputReader {
	BufferedReader br;
	StringTokenizer st;

	public InputReader(InputStream in) {
		br = new BufferedReader(new InputStreamReader(in));
		st = null;
	}

	public String next() {
		while (st == null || !st.hasMoreTokens()) {
			try {
				st = new StringTokenizer(br.readLine());
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
		}
		return st.nextToken();
	}

	public int nextInt() {
		return Integer.parseInt(next());
	}

	public long nextLong() {
		return Long.parseLong(next());
	}

	public double nextDouble() {
		return Double.parseDouble(next());
	}
}
