#include <bits/stdc++.h>
template <typename T>
T gcd(T a, T b) {
  return b == 0 ? a : gcd(b, a % b);
}
template <typename T>
T lcm(T a, T b) {
  return a * b / gcd(a, b);
}
template <typename T>
T clamp(T val, T min, T max) {
  return val < min ? min : (max < val ? max : val);
}
template <typename T>
size_t max_index(T begin, T end) {
  return distance(begin, max_element(begin, end));
}
template <typename T>
size_t min_index(T begin, T end) {
  return distance(begin, min_element(begin, end));
}
using namespace std;
signed main(void) {
  cin.tie(0);
  ios::sync_with_stdio(false);
  long long num = 0;
  long long n;
  cin >> n;
  long long q;
  cin >> q;
  string s;
  cin >> s;
  vector<long long> v(n);
  for (long long i = 0; i < n; ++i) v[i] = 1;
  for (long long i = 0; i < q; ++i) {
    char t, d;
    cin >> t >> d;
    for (long long j = 0; j < n; ++j) {
      if (s[j] == t) {
        if (d == 'L') {
          if (j - 1 >= 0) {
            v[j - 1] += v[j];
          }
          v[j] = 0;
        } else {
          if (j + 1 < n) {
            v[j + 1] += v[j];
          }
          v[j] = 0;
        }
      }
    }
  }
  num = accumulate(v.begin(), v.end(), 0);
  cout << num << endl;
  return 0;
}
