#ifndef DEBUG
#  define NDEBUG
#endif
#include <iostream>
#include <algorithm>
#include <string>
#include <iterator>
#include <utility>
#include <type_traits>
#include <limits>
#include <cassert>
#include <numeric>
#include <vector>
#include <array>

using namespace std;

// template {{{
// misc {{{
using Z = long long;
[[maybe_unused]]
constexpr Z INF = numeric_limits<Z>::max() / 3;
// }}}

// debug {{{
template <class T>
using enable_if_sequence_t = enable_if_t<
  is_same<
    typename iterator_traits<
      typename remove_cv_t<remove_reference_t<T>>::iterator
    >::iterator_category,
    random_access_iterator_tag>{}>;
#ifdef NDEBUG
# define dump(x)
# define debug if (0)
template <class T>
inline T&& ix(T&& value) { return value; }
template <class T, class Index, class... Indices, class = enable_if_sequence_t<T>>
inline auto&& ix(T&& container, Index index, Indices... indices) {
  return ix(container[index], indices...);
}
#else
# define dump(x) do { \
    cerr << "\e[33m[dump: " << __LINE__ << "] " << (#x) << " = " << x << "\e[0m" << endl; \
  } while (0);
# define debug
template <class T>
inline auto&& ix_impl([[maybe_unused]] int line, [[maybe_unused]] const char* code, T&& value) {
  return value;
}
template <class T, class Index, class... Indices, class = enable_if_sequence_t<T>>
inline auto&& ix_impl(int line, const char* code, T&& container, Index index, Indices... indices) {
  if (index < 0) {
    cerr << "\e[31mix: negative index at line " << line << ", ix(" << code << ")\n"
      << "index = " << index << "\e[0m" << endl;
    exit(1);
  }
  int size = distance(begin(container), end(container));
  if (index >= size) {
    cerr << "\e[31mix: index out of range at line " << line << ", ix(" << code << ")\n"
      << "index = " << index << " whereas size = " << size << "\e[0m" << endl;
    exit(1);
  }
  return ix_impl(line, code, container[index], indices...);
}
#define ix(...) ix_impl(__LINE__, #__VA_ARGS__, __VA_ARGS__)
#endif
// }}}

// IO {{{
template <class T, class U>
ostream& operator<< (ostream& os, pair<T, U> p) {
  os << '(' << p.first << ", " << p.second << ')';
  return os;
}
template <class T, class U>
istream& operator>> (istream& is, pair<T, U>& p) {
  is >> p.first >> p.second;
  return is;
}
template <class T>
false_type is_container_impl(...);
template <class T, class = typename T::iterator>
true_type is_container_impl(T);
template <class T>
struct is_container : decltype(is_container_impl<T>(declval<T>())) {};
template <>
struct is_container <string> : std::false_type {};
template <class Container, class = enable_if_t<is_container<Container>{}>>
istream& operator>> (istream& is, Container& cont) {
  for (auto& v : cont) is >> v;
  return is;
}
template <class Container, class = enable_if_t<is_container<Container>{}>>
ostream& operator<< (ostream& os, Container const& cont) {
  bool first = true;
  constexpr char sep =
    is_container<typename Container::value_type>{} ? '\n' : ' ';
  for (auto const& v : cont) {
    if (!first) {
      os << sep;
    }
    first = false;
    os << v;
  }
  return os;
}
// }}}
// }}}


template <class T, class F>
T boundary(F is_ok, T ok, T ng) {
  while (abs(ok - ng) > 1) {
    T m = (ok + ng) / 2;
    (is_ok(m) ? ok : ng) = m;
  }
  return ok;
}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.precision(10);
  cout << fixed;
  Z N, Q;
  string s;
  cin >> N >> Q >> s;
  vector<char> ts(Q);
  vector<Z> ds(Q);
  for (auto i = 0; i < Q; i++) {
    char c;
    cin >> ix(ts, i) >> c;
    ix(ds, i) = c == 'L' ? -1 : 1;
  }
  dump(ds);
  Z remain_left = boundary<Z>([&] (Z k) {
      if (k == N) return true;
      for (auto i = 0; i < Q; i++) {
        if (ix(s, k) != ix(ts, i)) {
          continue;
        }
        k += ix(ds, i);
        if (k == -1) {
          return false;
        }
        if (k == N) {
          return true;
        }
      }
      return true;
    }, N, -1);
  Z remain_right = boundary<Z>([&] (Z k) {
      if (k == -1) return true;
      for (auto i = 0; i < Q; i++) {
        if (ix(s, k) != ix(ts, i)) {
          continue;
        }
        k += ix(ds, i);
        if (k == -1) {
          return true;
        }
        if (k == N) {
          return false;
        }
      }
      return true;
    }, -1, N);
  dump(remain_left);
  dump(remain_right);
  if (remain_left == N || remain_right == -1) {
    cout << 0 << '\n';
  }
  else {
    cout << remain_right - remain_left + 1 << '\n';
  }
}



Measured memory_bytes: 2384