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 <string>
using namespace std;
using i64 = long long;
using u64 = unsigned long long;
#define REP(i, n) for (int i = 0; (i64)(i) < (i64)(n); ++i)

const int QMAX = 200000;
char T[QMAX], D[QMAX];

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  int N, Q;
  cin >> N >> Q;
  cin.ignore();
  string board;
  getline(cin, board);
  REP(i, Q) { cin >> T[i] >> D[i]; }
  int head = -1, tail = N;
  for (int i = Q - 1; i >= 0; --i) {
    char t = T[i];
    if (D[i] == 'L') {
      if (head + 1 < N && t == board[head + 1]) ++head;
      if (tail < N && t == board[tail]) ++tail;
    } else {
      if (tail - 1 >= 0 && t == board[tail - 1]) --tail;
      if (head >= 0 && t == board[head]) --head;
    }
  }
  cout << (tail - head - 1) << endl;
}
