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;

#define RFOR(type, i, a, b) for (type i = (b)-1;i >= (a); --i)
#define REP(type, i, n) for (type i = 0; i < (n); ++i)

int main(void) {
  long N, Q; cin >> N >> Q;
  string s; cin >> s;
  vector<pair<char, char> > input(Q);
  REP(long, i, Q) {
    char t, d; cin >> t >> d;
    input.at(i) = make_pair(t, d);
  }

  long l = -1, r = N;
  RFOR(long, i, 0, Q) {
    char t = input.at(i).first, d = input.at(i).second;
    if (d == 'L') {
      if (l < N-1 && t == s[l+1]) l++;
      if (r < N && t == s[r]) r++;
    } else {
      if (l > -1 && t == s[l]) l--;
      if (r > 0 && t == s[r-1]) r--;
    }
  }
  cout << r-l-1 << endl;

  return 0;
}
