There are N squares numbered 1 to N from left to right. Each square has a character written on it, and Square i has a letter s_i. Besides, there is initially one golem on each square.

Snuke cast Q spells to move the golems.

The i-th spell consisted of two characters t_i and d_i, where d_i is `L` or `R`. When Snuke cast this spell, for each square with the character t_i, all golems on that square moved to the square adjacent to the left if d_i is `L`, and moved to the square adjacent to the right if d_i is `R`.

However, when a golem tried to move left from Square 1 or move right from Square N, it disappeared.

Find the number of golems remaining after Snuke cast the Q spells.

Constraints

* 1 \leq N,Q \leq 2 \times 10^{5}
* |s| = N
* s_i and t_i are uppercase English letters.
* d_i is `L` or `R`.

Input

Input is given from Standard Input in the following format:


N Q
s
t_1 d_1
\vdots
t_{Q} d_Q


Output

Print the answer.

Examples

Input

3 4
ABC
A L
B L
B R
A R


Output

2


Input

8 3
AABCBDBA
A L
B R
A R


Output

5


Input

10 15
SNCZWRCEWB
B R
R R
E R
W R
Z L
S R
Q L
W L
B R
C L
A L
N L
E R
Z L
S L


Output

3
import java.util.*;
import java.io.*;

/**
 * 
 * @author glycine
 *
 */
public class Main {
	int N, Q;
	String s;
	char[] t, d;
	Map<Character, List<Integer>> cellTypes;
	int[] positions;

	int result;

	Main() throws IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		String[] tokens = in.readLine().split(" ");
		N = Integer.parseInt(tokens[0]);
		Q = Integer.parseInt(tokens[1]);
		s = in.readLine();
		t = new char[Q];
		d = new char[Q];
		for (int i = 0; i < Q; ++i) {
			tokens = in.readLine().split(" ");
			t[i] = tokens[0].charAt(0);
			d[i] = tokens[1].charAt(0);
		}
		in.close();
	}

	void calc() {
		int left = -1;
		int right = N;
		for (int i = Q - 1; i >= 0; --i) {
			char c = t[i];
			char dir = d[i];
			if (dir == 'L') {
				if (left <= N - 2 && s.charAt(left + 1) == c) {
					++left;
				}
				if (right <= N - 1 && s.charAt(right) == c) {
					right++;
				}
			} else {
				if (right > 0 && s.charAt(right - 1) == c) {
					--right;
				}
				if (left >= 0 && s.charAt(left) == c) {
					left--;
				}
			}
		}
		this.result = N;
		if (left >= 0)

		{
			this.result -= (left + 1);
		}
		if (right <= N - 1) {
			this.result -= (N - right);
		}
		this.result = Math.max(0, this.result);

	}

	public static void main(String[] args) throws IOException {
		Main ins = new Main();
		ins.calc();
		System.out.println(ins.result);

	}

}