#include <bits/stdc++.h>

using namespace std;

#define pb push_back
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
#define all(a) (a).begin(),(a).end()
#define endl "\n"
#define rep(i, a, b) for (auto (i) = (a); (i) < (b); (i)++)
#define rrep(i, a, b) for (auto (i) = (a); (i) > (b); (i)--)
#define UNIQUE(v) (v).erase(unique((v).begin(), (v).end()), (v).end());
#define BEGIN_SOLVER class Solver{public:
#define END_SOLVER };

#ifdef LOCAL_DEFINE
struct InitInput{
  InitInput() {
    FILE *stream1;
    stream1 = freopen("/Users/aim_cpo/CLionProjects/competitive/in.txt", "r", stdin);
    assert(stream1 != nullptr);
    cerr << "This problem is not interactive" << endl;
  }
}LOCAL_INPUT;
struct LOCAL_OUTPUT{
  LOCAL_OUTPUT() {
    FILE *stream2;
    const char *outputfile = "out.txt";
    stream2 = freopen(outputfile, "w", stdout);
    assert(stream2 != nullptr);
    cerr << "output [ " << outputfile << " ]" << endl;
  }
}/*LOCAL_OUTPUT*/;
#define show(x) cerr << #x << " = " << (x) << " (line " << __LINE__ << ")" << endl
#define showA(a, n) do{\
for(int _i_t_e_=0;_i_t_e_<(n);_i_t_e_++)\
cerr<<"("<<_i_t_e_<<" = "<<(a)[_i_t_e_]<<") ";\
cerr<<endl;}while(0)
#define showA2(a, n, m) do{\
for(int _i_t_e_=0;_i_t_e_<(n);_i_t_e_++){\
for(int _i_t_e_2=0;_i_t_e_2<(m);_i_t_e_2++){\
cerr<<"("<<_i_t_e_<<", "<<_i_t_e_2<<" = "<<(a)[_i_t_e_][_i_t_e_2]<<") ";\
}cerr<<endl;}cerr<<endl;}while(0)
#else
#define show(x)
#define showA(a, n)
#define showA2(a, n, m)
#endif

struct InitAim{
  InitAim() {
    ios::sync_with_stdio(false);cin.tie(nullptr);
    cout.precision(12);cout<<fixed;
#ifdef LOCAL_DEFINE
    cerr << "This problem is not interactive" << endl;
#endif
  }
}aim_cpo;

typedef long long ll;

constexpr const int INT_INF=0x3f3f3f3f; //1061109567
constexpr const ll LL_INF=0x3f3f3f3f3f3f3f3f; //4557430888798830399

template <typename T> bool chmin(T &a, T b){return a>b?(a=b,true):false;}
template <typename T> bool chmax(T &a, T b){return a<b?(a=b,true):false;}
template <typename T> void ln(T i, T n){cout<<(i==n-1?"\n":" ");}
template<typename T, typename S>
ostream &operator<<(ostream &out, const pair<T, S> &pair1) {
  out << '(' << pair1.fi << ", " << pair1.se << ')';
  return out;
}
template<typename T>
ostream &operator<<(ostream &out, const vector<T> &vector1) {
  out << '[';
  for (unsigned int i = 0; i < vector1.size(); i++) {
    out << vector1[i];
    if (i == vector1.size() - 1)out << "]"; else out << ", ";
  }
  return out;
}

// INT
#define GCD(a, b) __gcd(a, b)
template <typename T> T LCM(T a, T b) {return a / GCD(a, b) * b;}
template <typename T> T EXTGCD(T a, T b, T& x, T& y) {
  T d = a;
  if (b != 0) {d=EXTGCD(b,a%b,y,x);y-=(a/b)*x;}
  else x=1,y=0;
  return d;
}
template <typename T> bool is_prime(T a) {
  for(int i=2;i*i<=a;i++)if(a%i==0)return true;
  return false;
}
template <typename T, typename S> T Pow(T a, S b) {
  T res = 1, now = a;
  while(b){if(b&1)res*=now;b>>=1;now*=now;}return res;
}

// MOD
ll MOD = 1000000000L + 7L;
#define add(a, b) (((a) % MOD) + ((b) % MOD)) % MOD
#define mul(a, b) (((a) % MOD) * ((b) % MOD)) % MOD
#define sub(a, b) (((a) % MOD) + MOD - ((b) % MOD)) % MOD
template <typename T, typename S> T ModPow(T a, S b) {
  assert(b >= 0);
  T res = 1, now = sub(a, 0);
  while(b){if(b&1)res=mul(res,now);b>>=1;now=mul(now,now);}return res;
}
template <typename T> T mod_inverse(T a, T mod, bool prime){ // if mod is prime, "prime" is true.
  if(prime)return ModPow(a, mod - 2);
  else{T x,y;EXTGCD(a,mod,x,y);return (mod+x%mod)%mod;}
}
template <typename T> T EulerTotient(T a) {
  vector <pair <int, int> > v;
  for (T i = 2; i * i <= a; i++) {
    int cnt = 0;
    while (a % i == 0) {cnt++; a /= i;}
    if (cnt != 0) v.emplace_back(i, cnt);
  }
  if (a != 1) v.emplace_back(a, 1);
  //showV(v, (int) v.size());
  T res = 1;
  for (int i = 0; i < (int) v.size(); i++) {
    if (v[i].se == 1) {
      //res *= v[i].fi - 1;
      res = mul(res, v[i].fi - 1);
    } else {
      //res *= Pow(v[i].fi, v[i].se) - Pow(v[i].fi, v[i].se - 1);
      res = mul(res, sub(ModPow(v[i].fi, v[i].se), ModPow(v[i].fi, v[i].se - 1)));
    }
  }
  return res;
}
#define divide(a, b) mul(((a) % MOD), (mod_inverse((b), MOD, true))) % MOD
ll comb(ll a, ll b) {
  chmin(b, a - b);
  ll res = 1LL, now = a;
  for (ll i = 1; i <= b; i++) {
    res = mul(res, now); //res *= now;
    res = divide(res, i); // res /= i;
    now--;
  }
  return res;
}
// 735134400 約数が1344個ある高度合成数(<= 1e9)
// 897612484786617600 約数が103680個ある高度合成数(<= 1e18)
// 苦手分野 重複順列
// LLの数値をつかう時は最後にLLをつける癖をつけよう

BEGIN_SOLVER

///////////////////////////////////////////////////////////////////////////////////
// SOLVER
///////////////////////////////////////////////////////////////////////////////////

Solver(){
  input();
  solve();
}

///////////////////////////////////////////////////////////////////////////////////
// VARIABLE
///////////////////////////////////////////////////////////////////////////////////

int n, q;
string s;
char t[200001], d[200001];

///////////////////////////////////////////////////////////////////////////////////
// INPUT
///////////////////////////////////////////////////////////////////////////////////

void input(){
  cin >> n >> q;
  cin >> s;
  rep(i, 0, q) cin >> t[i] >> d[i];
}

///////////////////////////////////////////////////////////////////////////////////
// SOLVE
///////////////////////////////////////////////////////////////////////////////////

int BinarySearch(string &s) {
  int ok = -1, ng = n + 1;
  while (ng - ok > 1) {
    int mid = (ng + ok) / 2;
    auto check = [&](int mid) {
      if (mid == -1) return true;
      int now = mid;
      char nowc = s[mid];
      rep(i, 0, q) {
        if (nowc != t[i]) continue;
        if (d[i] == 'L') {
          now--;
        } else {
          now++;
        }
        if (now < 0) return false;
        if (now > n - 1) return true;
        nowc = s[now];
      }
      if (now >= 0) return true;
    };
    if (check(mid)) ng = mid;
    else ok = mid;
  }
  return ok;
}

void solve(){
  int ans = n;
  ans -= BinarySearch(s) + 1;
  reverse(all(s));
  rep(i, 0, q) {
    if (d[i] == 'L') d[i] = 'R';
    else d[i] = 'L';
  }
  ans -= BinarySearch(s) + 1;
  cout << ans << endl;
}

///////////////////////////////////////////////////////////////////////////////////
// OUTPUT
///////////////////////////////////////////////////////////////////////////////////

void output(){
}

///////////////////////////////////////////////////////////////////////////////////
// NOTE
///////////////////////////////////////////////////////////////////////////////////


///////////////////////////////////////////////////////////////////////////////////
// TEMPLATE(data structure)
///////////////////////////////////////////////////////////////////////////////////

class UnionFind {
public:
  explicit UnionFind(int _n) : n(_n) {
    par.resize(_n);
    rank.resize(_n);
    sizes.resize(_n);
    for (int i = 0; i < _n; i++) {
      par[i] = i;
      rank[i] = 0;
      sizes[i] = 1;
    }
  }
  int find(int a) {
    if (par[a] == a) return a;
    return par[a] = find(par[a]);
  }
  bool same(int a, int b) {
    return find(a) == find(b);
  }
  void unite(int a, int b) {
    link(find(a), find(b));
  }
  int size(int a) {
    return sizes[find(a)];
  }
  void view() {
    for (int i = 0; i < n; i++) {
      cout << " par" << "[" << i << "]=" << par[i] << ((i == n - 1) ? "\n" : ",");
    }
    for (int i = 0; i < n; i++) {
      cout << "size" << "[" << i << "]=" << sizes[i] << ((i == n - 1) ? "\n" : ",");
    }
    cout << endl;
  }
private:
  void link(int a, int b) {
    if (same(a, b)) return;
    if (rank[a] > rank[b]) {
      par[b] = a;
      sizes[a] += sizes[b];
      sizes[b] = 0;
    } else {
      par[a] = b;
      if (rank[a] == rank[b]) rank[b]++;
      sizes[b] += sizes[a];
      sizes[a] = 0;
    }
  }
  int n;
  vector<int> par;
  vector<int> rank;
  vector<int> sizes;
};

template <typename T>
class IntervalTree {
  using F = function<T(T, T)>;
public:
  IntervalTree(int n, const F func, const T init) : func(func), init(init) {
    size = 1;
    while ((int)size < n) size <<= 1;
    table.assign(2 * size, init);
  }
  void set(int k, T x) {
    table[size + k] = x;
  }
  void build() {
    for (int i = size - 1; i >= 0; --i) {
      table[i] = func(table[i * 2], table[i * 2 + 1]);
    }
  }
  void update(int k, const T &x) {
    k += size;
    table[k] = x;
    while (k >>= 1) {
      table[k] = func(table[k * 2], table[k * 2 + 1]);
    }
  }
  T query(int a, int b) {
    T L = init, R = init;
    for (a += size, b += size; a < b; a >>= 1, b >>= 1) {
      if (a & 1) L = func(L, table[a++]);
      if (b & 1) R = func(table[--b], R);
    }
    return func(L, R);
  }
  T operator[](const int k) const {
    return table[k + size];
  }
private:
  unsigned int size;
  vector<T> table;
  const F func;
  const T init;
};

template <typename T, typename S = T>
class LazyIntervalTree {
  using F = function<T(T, T)>;
  using G = function<T(T, S, int)>;
  using H = function<S(S, S)>;
public:
  LazyIntervalTree(int n, const F f, const G g, const H h, const T &init, const S OM)
    : f(f), g(g), h(h), init(init), OM(OM) {
    size = 1;
    while (size < n) size <<= 1;
    data.assign(2 * size, init);
    lazy.assign(2 * size, OM);
  }
  void set(int k, const T &x) {
    data[k + size] = x;
  }
  void build() {
    for (int i = size - 1; i > 0; i--) {
      data[i] = f(data[2 * i], data[2 * i + 1]);
    }
  }
  void propagate(int k, int len) {
    if (lazy[k] != OM) {
      if (k < size) {
        lazy[2 * k] = h(lazy[2 * k], lazy[k]);
        lazy[2 * k + 1] = h(lazy[2 * k + 1], lazy[k]);
      }
      data[k] = g(data[k], lazy[k], len);
      lazy[k] = OM;
    }
  }
  T update(int a, int b, const S &x, int k, int l, int r) {
    propagate(k, r - l);
    if (r <= a || b <= l) {
      return data[k];
    } else if (a <= l && r <= b) {
      lazy[k] = h(lazy[k], x);
      propagate(k, r - l);
      return data[k];
    } else {
      return data[k] = f(update(a, b, x, 2 * k, l, (l + r) >> 1),
                         update(a, b, x, 2 * k + 1, (l + r) >> 1, r));
    }
  }
  T update(int a, int b, const S &x) {
    return update(a, b, x, 1, 0, size);
  }
  T query(int a, int b, int k, int l, int r) {
    propagate(k, r - l);
    if (r <= a || b <= l) {
      return init;
    } else if (a <= l && r <= b) {
      return data[k];
    } else {
      return f(query(a, b, 2 * k, l, (l + r) >> 1),
               query(a, b, 2 * k + 1, (l + r) >> 1, r));
    }
  }
  T query(int a, int b) {
    return query(a, b, 1, 0, size);
  }
  T operator[](const int &k) {
    return query(k, k + 1);
  }
private:
  int size;
  vector <T> data;
  vector <S> lazy;
  const F f;
  const G g;
  const H h;
  const T init;
  const S OM;
};

template <typename T>
class BIT {
public:
  BIT(int size) {
    BITTable.assign(++size, 0);
  }
  T sum(int k) {
    T res = 0;
    for (++k; k > 0; k -= k & -k) {
      res += BITTable[k];
    }
    return res;
  }
  T sum(int l, int r) { // [l, r]
    if (l == 0) return sum(r);
    return sum(r) - sum(l - 1);
  }
  void update(int k, T x) { // b[k] += x;
    for (++k; k < (int)BITTable.size(); k += k & -k) BITTable[k] += x;
  }
private:
  vector<T> BITTable;
};

END_SOLVER

///////////////////////////////////////////////////////////////////////////////////
// MAIN
///////////////////////////////////////////////////////////////////////////////////

int main() {
  Solver ans;
#ifdef LOCAL_DEFINE
  cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << "s." << endl;
  show(MOD);
#endif
  return 0;
}

Measured memory_bytes: 976