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 <string>
#include <algorithm>
#include <bitset>
#include <iostream>

using namespace std;

int n, q;
string a[200005], b[200005], c, d, st;

int main() {
  cin >> n >> q >> st;
  
  for (int i = 0; i < q; ++i) {
    cin >> a[i] >> b[i];
  }

  int l = -1, r = n;
  for (int i = q-1; i >= 0; --i) {
    c = a[i];
    d = b[i];

    if (d[0] == 'L') {
      if (st[l + 1] == c[0]) {
        ++ l;
      }

      if (r < n && st[r] == c[0]) {
        ++ r;
      }
    } else {
      if (st[r - 1] == c[0]) {
        -- r;
      }

      if (l >= 0 && st[l] == c[0]) {
        -- l;
      }
    }
  }
  
  cout << r - l - 1 << endl;
  return 0;
}

