#pragma GCC optimize("Ofast")
#include<bits/stdc++.h>
using namespace::std;
struct __INIT{__INIT(){cin.tie(0);ios::sync_with_stdio(false);cout<<fixed<<setprecision(15);}} __init;
#define endl "\n"
#include <boost/multiprecision/cpp_dec_float.hpp>
#include <boost/multiprecision/cpp_int.hpp>
#include <boost/numeric/interval.hpp>
#include <boost/numeric/interval/io.hpp>
#include <boost/any.hpp>
using namespace::std;
namespace mp = boost::multiprecision;
typedef mp::number<mp::cpp_dec_float<32,int64_t>> cfloat;
typedef mp::cpp_int cint;
typedef long long lint;
typedef long long ll;
typedef long double ldouble;
typedef vector<lint> vec;
typedef vector<vector<lint>> mat;
typedef vector<vector<vector<lint>>> mat3;
typedef vector<double> dvec;
typedef vector<vector<double>> dmat;
typedef vector<vector<vector<double>>> dmat3;
typedef vector<string> svec;
typedef vector<vector<string>> smat;
typedef vector<vector<vector<string>>> smat3;
typedef vector<pair<lint,lint>> pvec;
typedef vector<vector<pair<lint,lint>>> pmat;
typedef vector<vector<vector<pair<lint,lint>>>> pmat3;
#define rep(i, n) for(lint i = 0; i < (lint)(n); i++)
#define irep(i) for(lint i = 0;; i++)
#define irep1(i) for(lint i = 1;; i++)
#define irep2(i) for(lint i = 2;; i++)
#define rrep(i, n) for(lint i = (lint)(n-1); i >-1; i--)
#define rrepi(i,a,b) for(lint i = (lint)(b-1); i >a-1; i--)
#define repi(i,a,b) for(lint i=lint(a);i<lint(b);i++)
#define rep2(i,a,b,c) for(lint i=lint(a);i>lint(b);i+=c)
#define all(x) (x).begin(),(x).end()
#define PI 3.141592653589793
#define dist(x1,y1,x2,y2) (pow(pow(x2-x1,2)+pow(y2-y1,2),0.5))
#define output(v) do{bool f=0;for(auto i:v){cout<<(f?" ":"");if(i>INF/2)cout<<"INF";else cout<<i;f=1;}cout<<"\n";}while(0)
#define output2(v) for(auto j:v)output(j);
#define input(a,n) lint n;cin>>n;vector<lint>a(n);rep(i,n)cin>>a[i];
#define SUM(v) accumulate(all(v),0LL)
#define INF (1LL<<60)
#define IINF (1<<30)
#define LINF 9223372036854775807
#define MOD 1000000007
inline lint gcd(lint a,lint b){return b?gcd(b,a%b):a;}
inline lint lcm(lint a,lint b){return a*b/gcd(a,b);}
inline bool chmin(auto& s,const auto& t){bool res=s>t;s=min(s,t);return res;}
inline bool chmax(auto& s,const auto& t){bool res=s<t;s=max(s,t);return res;}
inline lint mex(vector<lint> s){
    lint res=0;
    sort(all(s));
    while(binary_search(all(s),res))res++;
    return res;
}
vector<lint> dx={-1,1,0,0,1,1,-1,-1};
vector<lint> dy={0,0,-1,1,1,-1,1,-1};
int main(){
    lint n,q;
    cin>>n>>q;
    string s;
    cin>>s;
    map<char,vec> m;
    rep(i,s.size())m[s[i]].push_back(i);
    set<lint>now={-1,n};
    vector<char> t(q),d(q);
    string a,b;
    rep(i,q){
        cin>>a>>b;
        t[i]=a[0];
        d[i]=b[0];
    }
    reverse(all(t));
    reverse(all(d));
    rep(i,q){
        vec next,del;
        for(lint j:now){
            if(d[i]=='L'){
                if(j+1<n&&s[j+1]==t[i])next.push_back(j+1);
                if(0<=j&&j<n&&s[j]==t[i])del.push_back(j);
            }
            if(d[i]=='R'){
                if(j-1>=0&&s[j-1]==t[i])next.push_back(j-1);
                if(0<=j&&j<n&&s[j]==t[i])del.push_back(j);
            }
        }
        for(lint j:del)now.erase(j);
        for(lint j:next)now.insert(j);
    }
    cout<<n-(now.size()-2);
}