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
/*
* @Author Silviase(@silviasetitech)
* For ProCon
*/

import java.util.*;
import java.lang.*;
import java.math.*;

class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        
        // mazu input
        int n = sc.nextInt();
        int q = sc.nextInt();
        String s = sc.next();
        String[] choice = new String[q];
        String[] lORr = new String[q];
        for (int i = 0; i < q; i++) {
            choice[i] = sc.next();
            lORr[i] = sc.next();
        }
        int pivotl = -1;
        int pivotr = n;

        for (int i = q-1; i >= 0; i--) {
            if (lORr[i].equals("L")) {
                if (s.charAt(pivotl + 1) == choice[i].charAt(0)  ){
                    pivotl++;
                }
                if (pivotr < n) {
                    if (s.charAt(pivotr) == choice[i].charAt(0)) {
                        pivotr++;
                    }
                }
            }else{ // R
                if (s.charAt(pivotr - 1) == choice[i].charAt(0) ) {
                    pivotr--;
                }
                if (pivotl > -1) {
                    if (s.charAt(pivotl) == choice[i].charAt(0) ) {
                        pivotl--;
                    }
                }
            }
            if (pivotr-pivotl <= 1) {
                break;
            }
        }

        System.out.println(pivotr-pivotl-1);


        sc.close();
    }

}



