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;
int main() {
  int n, q;
  string s;
  cin >> n >> q >> s;
  vector<pair<char, char>> qry(q);
  for (int i = 0; i < q; i++) {
    char t, d;
    cin >> t >> d;
    qry[i] = {t, d};
  }
  int lft = 0;
  for(int i = q - 1; i >= 0; i--) {
    char t = qry[i].first;
    char d = qry[i].second;
    if (0 <= lft && t == s[lft] && d == 'L') {
      lft++;
    } else if (0 < lft && t == s[lft - 1] && d == 'R') {
      lft--;
    }
    if (lft == n) break;
  }
  int rgt = n;
  for(int i = q - 1; i >= 0; i--) {
    char t = qry[i].first;
    char d = qry[i].second;
    if (rgt < n && t == s[rgt] && d == 'L') {
      rgt++;
    } else if (rgt <= n && t == s[rgt - 1] && d == 'R') {
      rgt--;
    }
    if (rgt == -1) break;
  }
  int ret = rgt - lft;
  ret = max(ret, 0);
  cout << ret << '\n';
  return 0;
}