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 <algorithm>
#include <iostream>
#include <map>
#include <numeric>
#include <set>
#include <sstream>
#include <string>
#include <vector>
using namespace std;
typedef long long ll;

int main(int argc, const char * argv[]) {

  int N, Q;
  string s;
  cin >> N >> Q >> s;
  vector<char> t(Q), d(Q);
  for (int i=Q-1; i>=0; i--) {
    cin >> t[i] >> d[i];
  }
  
  int li, ri;
  li = 0;
  ri = N-1;
  for (int i=0; i<Q; i++) {
    if (d[i] == 'L'){
      if (s[li] == t[i])
        li++;
      if (ri<N-1 && s[ri+1] == t[i])
        ri++;
    }else{
      if (s[ri] == t[i])
        ri--;
      if (li>0 && s[li-1] == t[i])
        li--;
    }
  }
  cout << max(ri - li + 1, 0) << endl;
  
  return 0;
}