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 <algorithm>
#include <cmath>
#include <climits>
#include <cstdlib>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <vector>
#define DEBUG 1
constexpr int kMod = 1000000007;
typedef long long LL;

int main() {
  int N, Q; std::cin >> N >> Q;
  std::string S; std::cin >> S;

  std::string ts, ds;
  for (int i = 0; i < Q; ++i) {
    char t, d; std::cin >> t >> d;
    ts += t; ds += d;
  }

  int l = 0, r = N - 1;
  for (int i = Q - 1; i >= 0; --i) {
    if (ds[i] == 'L') {
      if (ts[i] == S[l]) ++l;
      if (r < N - 1 && ts[i] == S[r+1]) ++r;
    } else {
      if (l > 0 && ts[i] == S[l-1]) --l;
      if (ts[i] == S[r]) --r;
    }
  }

  std::cout << std::max(0, r - l + 1) << std::endl;
}
