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

using namespace std;

typedef long long int ll;
const int INF = 1<<30;
const long long LINF = 1LL<<60;

int main(){
    int n, q;
    string s;
    cin >> n >> q >> s;
    vector<pair<char, char>> t(q);
    for(int i = 0; i < q; i++){
        char a, b;
        cin >> a >> b;
        t[i] = make_pair(a, b);
    }
    int l = 0, r = n - 1;
    for(int i = q - 1; i >= 0; i--){
        if(l < n && t[i].first == s[l] && t[i].second == 'L'){
            l++;
        }else if(l > 0 && t[i].first == s[l - 1] && t[i].second == 'R'){
            l--;
        }
        if(r >= 0 && t[i].first == s[r] && t[i].second == 'R'){
            r--;
        }else if(r < n - 1 && t[i].first == s[r + 1] && t[i].second == 'L'){
            r++;
        }
        if(r < l) break;
    }
    cout << max(0, n - l - (n - 1 - r)) << endl;
    return 0;
}
