#include <bits/stdc++.h>
using namespace std;
#define int long long
#define stoi stoll
using ll=long long;
using vi=vector<int>;
using pii=pair<int,int>;
#define ALL(c) begin(c),end(c)
#define RALL(c) rbegin(c),rend(c)
#define ITR(i,b,e) for(auto i=(b);i!=(e);++i)
#define FORE(x,c) for(auto &&x:c)
#define REPF(i,a,n) for(int i=a,i##len=(int)(n);i<i##len;++i)
#define REP(i,n) REPF(i,0,n)
#define REPR(i,n) for(int i=(int)(n);i>=0;--i)
#define SZ(c) ((int)c.size())
#define CONTAIN(c,x) (c.find(x)!=end(c))
#define INSEG(l,x,r) ((l)<=(x)&&(x)<(r))
#define dump(...)
#define pb push_back
#define _ 0
const signed INF_=1001001001; const long long INF=1001001001001001001LL;
const int DX[9]={0,1,0,-1,1,1,-1,-1,0},DY[9]={-1,0,1,0,-1,1,1,-1,0};
template<class T> ostream& operator<<(ostream &os,const vector<T> &v) {
    ITR(i,begin(v),end(v))os<<*i<<(i==end(v)-1?"":" ");return os;}
template<class T> istream& operator>>(istream &is,vector<T> &v) {
    ITR(i,begin(v),end(v)) is>>*i;return is;}
template<class T,class U> istream& operator>>(istream &is, pair<T,U> &p) {
    is>>p.first>>p.second;return is;}
template<class T, class U> bool chmax(T &a,const U &b){return a<b?a=b,1:0;}
template<class T, class U> bool chmin(T &a,const U &b){return a>b?a=b,1:0;}
template <class T> void PSUM(T& c) {partial_sum(begin(c), end(c), begin(c));}
template<class T> using heap=priority_queue<T,vector<T>,greater<T>>;
struct before_main_function {
    before_main_function() {
        cin.tie(0); ios::sync_with_stdio(0);
        cout << setprecision(15) << fixed;
        // #define endl "\n"
    }
} before_main_function;
//------------------8<------------------------------------8<--------------------

signed main() {
    int N, Q;
    cin >> N >> Q;
    string s;
    cin >> s;
    vector<pair<char, char>> td(Q);
    REP(i, Q) {
        char t, d;
        cin >> t >> d;
        td[i] = {t, d};
    }

    auto check = [&](int i) -> int {
        int pos = i;
        REP(i, Q) {
            char t, d;
            tie(t, d) = td[i];
            if (t == s[pos]) {
                if (d == 'L') {
                    pos--;
                } else {
                    pos++;
                }
            }
            if (pos >= N) {
                return 1;
            }
            if (pos < 0) {
                return -1;
            }
        }
        return 0;
    };

    if (check(N - 1) == -1) {
        cout << 0 << endl;
        return 0;
    }

    if (check(0) == 1) {
        cout << 0 << endl;
        return 0;
    }

    int left, right;
    {
        int ok = N - 1;
        int ng = -1;
        while (abs(ok - ng) > 1) {
            int k = (ok + ng) / 2;
            if (check(k) == -1) {
                ng = k;
            } else {
                ok = k;
            }
        }
        left = ok;
    }
    {
        int ok = 0;
        int ng = N;
        while (abs(ok - ng) > 1) {
            int k = (ok + ng) / 2;
            if (check(k) == 1) {
                ng = k;
            } else {
                ok = k;
            }
        }
        right = ok;
    }
    dump(left, right);
    int ans = right - left + 1;
    if (ans < 0) ans = 0;
    cout << ans << endl;
    return (0^_^0);
}



Measured memory_bytes: 976