#include <bits/stdc++.h>
using namespace std;
struct node2 {
  int x;
  char y;
} z[200030];
int main() {
  int n, m;
  cin >> n >> m;
  for (int i = 0; i < n; i++) {
    cin >> z[i].y;
    z[i].x = 1;
  }
  char a, b;
  for (int i = 0; i < m; i++) {
    cin >> a >> b;
    if (b == 'L') {
      for (int j = 0; j < n; j++) {
        if (z[j].y == a) {
          if (j == 0) {
            z[j].x = 0;
            continue;
          }
          z[j - 1].x += z[j].x;
          z[j].x = 0;
        }
      }
    } else if (b == 'R') {
      for (int j = n - 1; j >= 0; j--) {
        if (z[j].y == a) {
          if (j == n - 1) {
            z[j].x = 0;
            continue;
          }
          z[j + 1].x += z[j].x;
          z[j].x = 0;
        }
      }
    }
  }
  int sum = 0;
  for (int i = 0; i < n; i++) {
    sum += z[i].x;
  }
  cout << sum << endl;
  return 0;
}
