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

#define NDEBUG
#include <cassert>


typedef long long ll;
typedef long double Double;
typedef unsigned long long ull;
typedef pair<int,int> ii;
typedef pair<ll,ll> llll;
typedef pair<double,double> dd;

typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef vector<ii> vii;
typedef vector<vector<ii>> vvii;
typedef vector<ll> vll;
typedef vector<string> vs;
typedef vector<double> vd;
typedef vector<long double> vD;

#define sz(a)  int((a).size())
#define pb  push_back
#define eb  emplace_back
#define FOR(var,from,to) for(int var=(from);var<=(to);++var)
#define rep(var,n)  for(int var=0;var<(n);++var)
#define rep1(var,n)  for(int var=1;var<=(n);++var)
#define repC2(vari,varj,n)  for(int vari=0;vari<(n)-1;++vari)for(int varj=vari+1;varj<(n);++varj)
#define ALL(c)  (c).begin(),(c).end()
#define RALL(c)  (c).rbegin(),(c).rend()
#define tr(i,c)  for(auto i=(c).begin(); i!=(c).end(); ++i)
#define found(s,e)  ((s).find(e)!=(s).end())
#define mset(arr,val)  memset(arr,val,sizeof(arr))
#define mid(x,y) ((x)+((y)-(x))/2)
#define IN(x,a,b) ((a)<=(x)&&(x)<=(b))
#define cons make_pair

#define PQ(T) priority_queue<T>
#define RPQ(T) priority_queue<T,vector<T>,greater<T>>

template<class T> inline void amin(T & a, T const & b) { a = min(a, b); }
template<class T> inline void amax(T & a, T const & b) { a = max(a, b); }

inline ll square(ll x) { return x * x; }
inline ll gcd(ll a, ll b) { while(a) swap(a, b%=a); return b; }
template <typename T>
inline T mod(T a, T b) { return ((a % b) + b) % b; }


const ll MOD=1000000007LL;

ll ADD(ll x, ll y) { return (x+y) % MOD; }
ll SUB(ll x, ll y) { return (x-y+MOD) % MOD; }
ll MUL(ll x, ll y) { return x*y % MOD; }
ll POW(ll x, ll e) { ll v=1; for(; e; x=MUL(x,x), e>>=1) if (e&1) v = MUL(v,x); return v; }
ll DIV(ll x, ll y) { /*assert(y%MOD!=0);*/ return MUL(x, POW(y, MOD-2)); }

char _buf[200000 + 3];

void read_cr() {
    fgets(_buf, 256, stdin);
}

int solve(int N, int Q, string &s, vi&t, vi&q) {

    int x, leftmost=0, rightmost=N-1;
    {
        int lo=-1, hi=N;
        while (lo+1 < hi) {
            int mi=(lo+hi)/2, x = mi;
            bool good=false;
            rep(i,Q){
                if (x<0) { good=true; break; }
                if (x == N) { break ;}
                if (t[i]==s[x]) {
                    if (q[i]=='R') ++x; else --x;
                }
            }
            if (x < 0) good = true;
            if (good) lo=mi;
            else hi=mi;
        }
        leftmost = lo+1;
    }
    {
        int lo=-1, hi=N;
        while (lo+1 < hi) {
            int mi=(lo+hi)/2, x = mi;
            bool good=false;
            rep(i,Q){
                if (x == N) { good=true; break; }
                if (x < 0) { break ;}
                if (t[i]==s[x]) {
                    if (q[i]=='R') ++x; else --x;
                }
            }
            if (x == N) good = true;
            if (good) hi=mi;
            else lo=mi;
        }
        rightmost = hi-1;
    }
    return max(0, rightmost - leftmost + 1);
}

int main() {
    int N,Q; scanf("%d%d", &N,&Q); read_cr();
    fgets(_buf, N+3, stdin);
    string s(_buf, _buf+N);
    vector<int> t(Q), d(Q);
    rep(i,Q) {
        fgets(_buf, 10, stdin);
        t[i]=_buf[0]; d[i]=_buf[2];
    }
    printf("%d\n", solve(N,Q,s,t,d));
    return 0;
}


Measured memory_bytes: 2176