# include <bits/stdc++.h>
using namespace std;
using LL = long long;
using ULL = unsigned long long;
const double PI = acos(-1);
template<class T>constexpr T INF() { return ::std::numeric_limits<T>::max(); }
template<class T>constexpr T HINF() { return INF<T>() / 2; }
template <typename T_char>T_char TL(T_char cX) { return tolower(cX); };
template <typename T_char>T_char TU(T_char cX) { return toupper(cX); };
template<typename T>vector<T> make_v(size_t a){ return vector<T>(a); }
template<typename T,typename... Ts>auto make_v(size_t a, Ts... ts){ return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...)); }
template<typename T,typename V>typename enable_if<is_class<T>::value==0>::type fill_v(T &t, const V &v){ t = v; }
template<typename T,typename V>typename enable_if<is_class<T>::value!=0>::type fill_v(T &t, const V &v){ for(auto &e : t) fill_v(e, v); }
const int vy[] = { -1, -1, -1, 0, 1, 1, 1, 0 }, vx[] = { -1, 0, 1, 1, 1, 0, -1, -1 };
const int dx[4] = { 0,1,0,-1 }, dy[4] = { 1,0,-1,0 };
int popcnt(unsigned long long n) { int cnt = 0; for (int i = 0; i < 64; i++)if ((n >> i) & 1)cnt++; return cnt; }
int d_sum(LL n) { int ret = 0; while (n > 0) { ret += n % 10; n /= 10; }return ret; }
int d_cnt(LL n) { int ret = 0; while (n > 0) { ret++; n /= 10; }return ret; }
LL gcd(LL a, LL b) { if (b == 0)return a; return gcd(b, a%b); };
LL lcm(LL a, LL b) { LL g = gcd(a, b); return a / g*b; };
# define ALL(qpqpq)           (qpqpq).begin(),(qpqpq).end()
# define UNIQUE(wpwpw)        sort(ALL((wpwpw)));(wpwpw).erase(unique(ALL((wpwpw))),(wpwpw).end())
# define LOWER(epepe)         transform(ALL((epepe)),(epepe).begin(),TL<char>)
# define UPPER(rprpr)         transform(ALL((rprpr)),(rprpr).begin(),TU<char>)
# define FOR(i,tptpt,ypypy)   for(LL i=(tptpt);i<(ypypy);i++)
# define REP(i,upupu)         FOR(i,0,upupu)
# define INIT                 std::ios::sync_with_stdio(false);std::cin.tie(0)

int n, q;
string s;
char t[202020];
char d[202020];

int main(){
    INIT;
    cin >> n >> q;
    int l = 1, r = n;
    cin >> s;
    s = " " + s;
    REP(i, q){
        cin >> t[i] >> d[i];
    }
    for(int i = q - 1;i >= 0;i--){
        if(d[i] == 'L' && s[l] == t[i])l++;
        if(d[i] == 'R' && s[l] == t[i])l--;
        if(d[i] == 'R' && s[r] == t[i])r--;
        if(d[i] == 'L' && s[r] == t[i])r++;
        r = min(n, r);
        l = max(1, l);
    }
    if(r < l){
        cout << l - r + 1 << endl;
    }else{
        cout << r - l + 1 << endl;
    }
}