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;

using ll = long long;
using P = pair<ll, ll>;

const int MAX = 2e5;

int main() {
  int N, Q;
  cin >> N >> Q;
  string s;
  cin >> s;
  char t[Q], d[Q];
  for (int i = 0; i < Q; i++) cin >> t[i] >> d[i];

  int left = -1, right = N;
  for (int i = Q - 1; i >= 0; i--) {
    if (d[i] == 'R') {
      if (t[i] == s[right - 1]) {
        right--;
      }
      if (left > -1 && t[i] == s[left]) {
        left--;
      }
    } else {
      if (t[i] == s[left + 1]) {
        left++;
      }
      if (right < N && t[i] == s[right]) {
        right++;
      }
    }
  }

  cout << max(right - left - 1, 0) << endl;
  return 0;
}
