#include <bits/stdc++.h>
using namespace std;

typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;
#define int ll

typedef pair<int, int> pii;
typedef pair<pii, pii> piii;
typedef vector<piii> vpii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector< vi > vvi;
typedef vector< vvi > vvvi;
typedef vector<pii> vpi;
typedef vector<short> vs;
typedef vector<vs> vvs;
typedef vector<vvs> vvvs;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<vvl> vvvl;
typedef vector<ld> vld;
typedef vector<vld> vvld;
typedef vector<vvld> vvvld;
typedef vector<string> vst;
typedef vector<vst> vvst;
typedef pair<ld, ld> pld;
typedef complex<double> base;

#define inmin(a, b) a = min(a, (b))
#define inmax(a, b) a = max(a, (b))
#define mp(a, b) make_pair(a, (b))
#define ALL(a) a.begin(),a.end()
#define RALL(a) a.rbegin(),a.rend()
#define sqr(x) ((x) * (x))
#define fori(i, n) for(int i = 0; i < int(n); ++i)
#define SZ(a) ((int)((a).size()))
#define triple(T) tuple<T, T, T>
#define quad(T) tuple<T, T, T, T>
#define watch(x) cout << (#x) << " = " << x << endl;
#ifdef MAX_HOME
#define cerr cout
#else
#define cerr if (false) cerr
#endif


void err(istream_iterator<string> it) {}
template<typename T, typename... Args>
void err(istream_iterator<string> it, T a, Args... args) {
    cerr << *it << " = " << a << endl;
    err(++it, args...);
}

const double PI = 2 * acos(0.0);

const string DIGITS = "0123456789";
const string ALPH = "abcdefghijklmnopqrstuvwxyz";


istream &operator >> (istream &in, pii &a)
{
    in >> a.first >> a.second;
    return in;
}


ostream &operator << (ostream &out, pii &a)
{
    out << a.first << ' ' << a.second;
    return out;
}


template <class T0, class T1>
inline ostream & operator << (ostream &out, pair<T0, T1> &a) {
    return out << "{" << a.first << ", " << a.second << "}";
}

template <class T0, class T1, class T2>
inline ostream & operator << (ostream &out, tuple<T0, T1, T2> &a) {
    return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a) << "}";
}

template <class T0, class T1, class T2, class T3>
inline ostream & operator << (ostream &out, tuple<T0, T1, T2, T3> &a) {
    return out << "{" << get<0>(a) << ", " << get<1>(a) <<
               ", " << get<2>(a) << ", " <<  get<3>(a) << "}";
}

template<class T>
inline ostream & operator << (ostream &out, vector<T> &a) {
    out << "[";
    fori (i, a.size())
        out << a[i] << vector<string>{", ", "]  "}[i + 1 == a.size()];
    return out;
}


void smain();

signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

#ifdef ART_HOME
    freopen("input.txt", "r", stdin);
    clock_t start = clock();
#endif
    cout << setprecision(12) << fixed;
    smain();
#ifdef ART_HOME
    cout << "\n\n\n\nTOTAL EXECUTION TIME: " << float( clock () - start ) /  CLOCKS_PER_SEC << endl;
#endif
}


const int N = 210, A = 20, X = 1 << 15, M = 1e9 + 7;


vector<pair<string, string>> chal;
string s;


bool check1(int ind)
{
    string f(1, s[ind]);
    int mn = 0;

    for (auto p : chal)
        if (f == p.first)
        {
            ind += p.second == "L" ? -1 : 1;
            f = (1, s[ind]);
            mn = min(mn, ind);
        }

    return mn < 0;
}


bool check2(int ind)
{
    string f(1, s[ind]);
    int mx = 0;

    for (auto p : chal)
        if (f == p.first)
        {
            ind += p.second == "L" ? -1 : 1;
            f = (1, s[ind]);
            mx = max(mx, ind);
        }

    return mx >= SZ(s);
}


void smain()
{
    int n, q;
    cin >> n >> q;
    cin >> s;

    chal.resize(q);
    for (int i = 0; i < q; ++i)
        cin >> chal[i].first >> chal[i].second;

    int l = -1, r = SZ(s);
    while (r - l > 1)
    {
        int m = (l + r) >> 1;

        if (check1(m))
            l = m;
        else
            r = m;
    }

    int ans = l + 1;


    l = -1, r = SZ(s);
    while (r - l > 1)
    {
        int m = (l + r) >> 1;

        if (check2(m))
            r = m;
        else
            l = m;
    }

    ans += SZ(s) - r;
    cout << n - min(ans, SZ(s));
}


Measured memory_bytes: 22352