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"bits/stdc++.h"
using namespace std;
using ll = int64_t;

int main() {
    ll N, Q;
    string s;
    cin >> N >> Q >> s;
    vector<char> t(Q), d(Q);
    for (ll i = 0; i < Q; i++) {
        cin >> t[i] >> d[i];
    }

    //[left, right]にあるものは生き残る
    ll left = 0, right = N - 1;

    for (ll i = Q-1;i>=0;i--) {
        if (d[i] == 'L') {
            if (t[i] == s[left]) {
                left++;
            }
            //範囲を広げている
            if (right < N-1 && t[i] == s[right+1]) {
                right++;
            }
        } else {
            if (t[i] == s[right]) {
                right--;
            }
            //範囲を広げている
            if (left > 0 && t[i] == s[left-1]) {
                left--;
            }
        }
    }

    cout << max(right - left + 1,(ll)0) << endl;
}
