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;
const int N = 200000 + 10;
char s[N];
int n,m;
char x[N],y[N];
int main(){
    ios::sync_with_stdio(0);
    cin>>n>>m;
    cin>>(s+1);
    for(int i=0;i<m;i++) cin>>x[i]>>y[i];
    int l = 0, r = n + 1;
    for(int i=m-1;i>=0;i--){
        if(y[i]=='L'){
            if(x[i]==s[l+1]) l++;
            if(x[i]==s[r]) r++;
        }
        else{
            if(x[i]==s[r-1]) r--;
            if(x[i]==s[l]) l--;
        }
        if(l+1>=r) break;
//        cout<<l<<' '<<r<<endl;
    }
    cout<<max(r-l-1,0)<<endl;
}
