#include <bits/stdc++.h>
using namespace std;
template <typename _KTy, typename _Ty>
ostream& operator<<(ostream& o, const pair<_KTy, _Ty>& m) {
  o << "{" << m.first << ", " << m.second << "}";
  return o;
}
template <typename _KTy, typename _Ty>
ostream& operator<<(ostream& o, const map<_KTy, _Ty>& m) {
  if (m.empty()) {
    o << "{ }";
    return o;
  }
  o << "{" << *m.begin();
  for (auto itr = ++m.begin(); itr != m.end(); itr++) {
    o << ", " << *itr;
  }
  o << "}";
  return o;
}
template <typename _KTy, typename _Ty>
ostream& operator<<(ostream& o, const unordered_map<_KTy, _Ty>& m) {
  if (m.empty()) {
    o << "{ }";
    return o;
  }
  o << "{" << *m.begin();
  for (auto itr = ++m.begin(); itr != m.end(); itr++) {
    o << ", " << *itr;
  }
  o << "}";
  return o;
}
template <typename _Ty>
ostream& operator<<(ostream& o, const vector<_Ty>& v) {
  if (v.empty()) {
    o << "{ }";
    return o;
  }
  o << "{" << v.front();
  for (auto itr = ++v.begin(); itr != v.end(); itr++) {
    o << ", " << *itr;
  }
  o << "}";
  return o;
}
template <typename _Ty>
ostream& operator<<(ostream& o, const set<_Ty>& s) {
  if (s.empty()) {
    o << "{ }";
    return o;
  }
  o << "{" << *(s.begin());
  for (auto itr = ++s.begin(); itr != s.end(); itr++) {
    o << ", " << *itr;
  }
  o << "}";
  return o;
}
template <typename _Ty>
ostream& operator<<(ostream& o, const unordered_set<_Ty>& s) {
  if (s.empty()) {
    o << "{ }";
    return o;
  }
  o << "{" << *(s.begin());
  for (auto itr = ++s.begin(); itr != s.end(); itr++) {
    o << ", " << *itr;
  }
  o << "}";
  return o;
}
template <typename _Ty>
ostream& operator<<(ostream& o, const stack<_Ty>& s) {
  if (s.empty()) {
    o << "{ }";
    return o;
  }
  stack<_Ty> t(s);
  o << "{" << t.top();
  t.pop();
  while (!t.empty()) {
    o << ", " << t.top();
    t.pop();
  }
  o << "}";
  return o;
}
template <typename _Ty>
ostream& operator<<(ostream& o, const list<_Ty>& l) {
  if (l.empty()) {
    o << "{ }";
    return o;
  }
  o << "{" << l.front();
  for (auto itr = ++l.begin(); itr != l.end(); ++itr) {
    o << ", " << *itr;
  }
  o << "}";
  return o;
}
template <typename _KTy, typename _Ty>
istream& operator>>(istream& is, pair<_KTy, _Ty>& m) {
  is >> m.first >> m.second;
  return is;
}
template <typename _Ty>
istream& operator>>(istream& is, vector<_Ty>& v) {
  for (size_t i = 0; i < v.size(); i++) is >> v[i];
  return is;
}
namespace aux {
template <typename Ty, unsigned N, unsigned L>
struct tp {
  static void print(ostream& os, const Ty& v) {
    os << get<N>(v) << ", ";
    tp<Ty, N + 1, L>::print(os, v);
  }
};
template <typename Ty, unsigned N>
struct tp<Ty, N, N> {
  static void print(ostream& os, const Ty& v) { os << get<N>(v); }
};
}  // namespace aux
template <typename... Tys>
ostream& operator<<(ostream& os, const tuple<Tys...>& t) {
  os << "{";
  aux::tp<tuple<Tys...>, 0, sizeof...(Tys) - 1>::print(os, t);
  os << "}";
  return os;
}
template <typename A, size_t N, typename T>
inline void Fill(A (&array)[N], const T& val) {
  std::fill((T*)array, (T*)(array + N), val);
}
void dump_func() { cerr << endl; }
template <class Head, class... Tail>
void dump_func(Head&& head, Tail&&... tail) {
  cerr << head;
  if (sizeof...(Tail) == 0) {
    cerr << " ";
  } else {
    cerr << ", ";
  }
  dump_func(std::move(tail)...);
}
int N, Q;
string s;
vector<char> t;
vector<char> d;
int finalPos(int p) {
  if (p < 0 || p >= N) return p;
  for (int q = (0); q < (Q); ++q) {
    if (s[p] != t[q]) continue;
    p += (d[q] == 'L' ? -1 : 1);
    if (p < 0 || p >= N) return p;
  }
  return p;
}
bool leftBound(int n) { return !(finalPos(n) == -1); }
bool rightBound(int n) { return !(finalPos(n) == N); }
template <typename T>
T BinarySearch(T ng, T ok, function<bool(T)> func) {
  while (abs(ok - ng) > 1) {
    T mid = (ng + ok) / 2;
    (func(mid) ? ok : ng) = mid;
  }
  return ok;
}
int solve() {
  int ans = 0;
  int l = BinarySearch<int>(-1, N - 1, leftBound);
  int r = BinarySearch<int>(N, 0, rightBound);
  return r - l + 1;
}
signed main() {
  std::ios::sync_with_stdio(false);
  std::cin.tie(0);
  cin >> N >> Q >> s;
  t.resize(Q);
  d.resize(Q);
  for (int i = (0); i < (Q); ++i) cin >> t[i] >> d[i];
  cout << solve() << endl;
  return 0;
}
