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
#include <cstdio>
#include <algorithm>

#define MAX_N 100010

using namespace std;

int main() {
    int n, q;
    scanf("%d %d", &n, &q);
    int d[q];
    char s[n+1], t[q+1]; t[q] = '\0';
    scanf("%s\n", s);
    for (int i=q-1; i>=0; i--) {
        char dc;
        scanf("\n%c %c", t+i, &dc);
        d[i] = (dc == 'R') ? 1 : -1;
    }
    int front = 0, back = 0;
    for (int i=0; i<q; i++) {
        if (front + back >= n) break;
        if (t[i] == s[front] && d[i] == -1)
            front++;
        else if (front > 0 && t[i] == s[front-1] && d[i] == 1)
            front--;
        if (t[i] == s[n-1-back] && d[i] == 1)
            back++;
        else if (back > 0 && t[i] == s[n-back] && d[i] == -1)
            back--;
    }
    printf("%d\n", max(n-front-back, 0));
    return 0;
}