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<iostream>
#include<string>
#include<algorithm>
#include<vector>

int n, q;
std::string s;
std::vector<char> t, d;

int abs(int x) {
    return x >= 0 ? x : x * -1;
}

bool goal(int cur) {
    for (int i = 0; i < q; i++) {
        if (s[cur] == t[i]) {
            cur = (d[i] == 'L') ? cur - 1 : cur + 1;
        }
        if (cur < 0 || n <= cur) {
            return false;
        }
    }
    return true;
}

int bsearch(int ok, int ng) {
    while (std::abs(ok - ng) > 1) {
        int mi = (ok + ng) / 2;
        if (goal(mi)) {
            ok = mi;
        } else {
            ng = mi;
        }
    } 
    return ok;
}


int main() {
    std::cin >> n >> q;
    std::cin >> s;

    t.resize(q);
    d.resize(q);
    for (int i = 0; i < q; i++) {
        std::cin >> t[i] >> d[i];
    }

    int x = bsearch(-1, n);
    int y = bsearch(n, -1);
    int z = x - y + 1;
    std::cout << std::max(0, z) << std::endl;
}