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.Scanner;

public class Main {
    public static void main(String [] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int q = scanner.nextInt();
        String s = scanner.next();
        String[] t = new String[q];
        String[] d = new String[q];
        for (int i = 0; i < q; ++i) {
            t[i] = scanner.next();
            d[i] = scanner.next();
        }
        // find leftDroppedMaxIndex
        int leftMaxIndex = -1;
        int index = 0;
        char current = s.charAt(0);
        for (int i = q - 1; i >= 0; --i) {
            if (d[i].equals("L") && t[i].charAt(0) == current) {
                leftMaxIndex = index;
                if (leftMaxIndex == s.length() - 1) {
                    break;
                }
                index++;
                current = s.charAt(index);
            } else if (d[i].equals("R") && index - 1 >= 0 &&
                    t[i].charAt(0) == s.charAt(index - 1)) {
                leftMaxIndex--;
                --index;
                current = s.charAt(index);
            }
        }

        // find rightDroppedMinIndex
        int rightMinIndex = s.length();
        index = s.length() - 1;
        current = s.charAt(index);
        for (int i = q - 1; i >= 0; --i) {
            if (d[i].equals("R") && t[i].charAt(0) == current) {
                rightMinIndex = index;
                if (rightMinIndex == 0) {
                    break;
                }
                --index;
                current = s.charAt(index);
            } else if (d[i].equals("L") && index + 1 < s.length() &&
                    t[i].charAt(0) == s.charAt(index + 1)) {
                rightMinIndex++;
                ++index;
                current = s.charAt(index);
            }
        }
        int leftDropped = leftMaxIndex + 1;
        int rightDropped = s.length() - rightMinIndex;
        System.out.println((n - leftDropped - rightDropped));

    }

}
