// vvvvvvvvvvvv TEMPLATE vvvvvvvvvvvv
#include <bits/stdc++.h>
using namespace std; using ll = long long; using P = pair<ll, ll>;
const ll linf = 1e18; const double eps = 1e-12, pi = acos(-1);
#define FOR(i,a,b) for (ll i=(a),__last_##i=(b);i<__last_##i;i++)
#define RFOR(i,a,b) for (ll i=(b)-1,__last_##i=(a);i>=__last_##i;i--)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) RFOR(i,0,n)
#define __GET_MACRO3(_1, _2, _3, NAME, ...) NAME
#define each(i,a) for (auto&& i : a)
#define rep(...) __GET_MACRO3(__VA_ARGS__, FOR, REP)(__VA_ARGS__)
#define rrep(...) __GET_MACRO3(__VA_ARGS__, RFOR, RREP)(__VA_ARGS__)
#define pb push_back
#define eb emplace_back
#define all(a) begin(a),end(a)
#define chmin(x,v) x = min(x, v)
#define chmax(x,v) x = max(x, v)
template<typename T> ll min(ll a, const T&& b) { return a < b ? a : b; }
template<typename T> ll min(const T&& a, ll b) { return a < b ? a : b; }
template<typename T> ll max(ll a, const T&& b) { return a > b ? a : b; }
template<typename T> ll max(const T&& a, ll b) { return a > b ? a : b; }
template<typename Head> void out(Head h) { cout << h << endl; } template<typename Head, typename... Tail>void out(Head h, Tail... t) { cout << h << " "; out(t...); }
template<typename T> istream& operator>>(istream& is, vector<T>& v) { each(x,v) is >> x; return is; }
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v) { rep(i,v.size()) { if (i) os << " "; os << v[i]; } return os; }
ostream& operator<<(ostream& os, const vector<string>& v) { rep(i,v.size()) { if (i) os << endl; os << v[i]; } return os; }
template<typename T> ostream& operator<<(ostream& os, const vector<vector<T>>& v) { rep(i,v.size()) { if (i) os << endl; os << v[i]; } return os; }
template<typename T1, typename T2> ostream& operator<<(ostream& os, const pair<T1, T2>& p) { return os << "(" << p.first << ", " << p.second << ")"; }
struct yes_no : std::numpunct<char> { string_type do_truename() const { return "Yes"; } string_type do_falsename() const { return "No"; } };
void solve(); int main() {
  ios::sync_with_stdio(false); cin.tie(0); locale loc(locale(), new yes_no); cout.imbue(loc); cout << fixed << setprecision(10) << boolalpha;
  solve();
}
// ^^^^^^^^^^^^ TEMPLATE ^^^^^^^^^^^^

void solve() {
  ll n, m; cin >> n >> m;
  string s; cin >> s;
  vector<string> t(m), d(m);
  rep(i, m) cin >> t[i] >> d[i];
  auto is_out_r = [&](ll x) {
    rep(i, m) {
      if (s[x] == t[i][0]) {
        if (d[i] == "L") {
          --x;
        }
        else {
          ++x;
        }
        if (x < 0) return false;
        if (x >= n) return true;
      }
    }
    return false;
  };
  auto is_out_l = [&](ll x) {
    rep(i, m) {
      if (s[x] == t[i][0]) {
        if (d[i] == "L") {
          --x;
        }
        else {
          ++x;
        }
        if (x < 0) return true;
        if (x >= n) return false;
      }
    }
    return false;
  };
  ll l, r;
  {
    ll lb = 0, ub = n;
    rep(t, 30) {
      ll mid = (lb + ub) / 2;
      if (is_out_r(mid)) {
        ub = mid;
      }
      else {
        lb = mid;
      }
    }
    r = ub;
  }
  {
    ll lb = 0, ub = n;
    rep(t, 30) {
      ll mid = (lb + ub) / 2;
      if (!is_out_l(mid)) {
        ub = mid;
      }
      else {
        lb = mid;
      }
    }
    l = ub;
  }
  cout << r-l << endl;
}


Measured memory_bytes: 22352