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.*;
public class Main {
    static int n;
    static String s;
    static int q;
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        n = sc.nextInt();
        q = sc.nextInt();
        s = sc.next();
        char[] t = new char[q];
        char[] d = new char[q];
        for (int i = 0; i < q; i++) {
            t[i] = sc.next().charAt(0);
            d[i] = sc.next().charAt(0);
        }
        int left = binSearch(t, d, -1, n);
        // System.out.println("left = " + left);
        int right = binSearch(t, d, n, -1);
        // System.out.println("right = " + right);
        int ans = Math.max(0, right - left - 1);
        System.out.println(ans);
    }
    public static int binSearch(char[] t, char[] d, int ok, int ng) {
        int out = ok;
        while (Math.abs(ok - ng) > 1) {
            int mid = (ok + ng) / 2;
            if (solve(mid, t, d, out)) {
                ok = mid;
            } else {
                ng = mid;
            }
            // System.out.printf("ok = %d,ng = %d %n", ok, ng);
        }
        return ok;
    }
    public static boolean solve(int mid, char[] t, char[] d, int out) {
        for (int i = 0; i < q; i++) {
            if (mid == -1 || mid == n) {
                return false;
            }
            char ch = s.charAt(mid);
            // System.out.println("ch = " + ch);
            // System.out.println("mid = " + mid);
            // System.out.printf("t[%d] = %s %n", i, t[i]);
            // System.out.printf("d[%d] = %s %n", i, d[i]);
            if (ch != t[i]) {
                continue;
            }
            if (d[i] == 'L') {
                mid--;
            } else if (d[i] == 'R') {
                mid++;
            }
            if (mid == out) {
                //    System.out.println("out mid = " + mid);
                return true;
            }
        }
        return false;
    }
}
