#include <iostream>
#include <fstream>
#include <iomanip>
#include <climits>
#include <limits>
#include <algorithm>
#include <vector>
#include <deque>
#include <queue>
#include <list>
#include <stack>
#include <string>
#include <functional>
#include <numeric>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <unordered_map>
#include <random>
#include <cmath>
#include <complex>

using namespace std;

using vi = vector<int>; using vvi = vector<vi>; using vvvi = vector<vvi>;
using ll = long long int;
using vll = vector<ll>; using vvll = vector<vll>; using vvvll = vector<vvll>;
using vd = vector<double>; using vvd = vector<vd>; using vvvd = vector<vvd>;
using P = pair<int, int>;
using Pll = pair<ll, ll>;
using cdouble = complex<double>;

const double eps = 1e-9;
const double INFD = numeric_limits<double>::infinity();
const double PI = 3.14159265358979323846;
#define Loop(i, n) for(int i = 0; i < (int)n; i++)
#define Loopll(i, n) for(ll i = 0; i < (ll)n; i++)
#define Loop1(i, n) for(int i = 1; i <= (int)n; i++)
#define Loopll1(i, n) for(ll i = 1; i <= (ll)n; i++)
#define Loopr(i, n) for(int i = (int)n - 1; i >= 0; i--)
#define Looprll(i, n) for(ll i = (ll)n - 1; i >= 0; i--)
#define Loopr1(i, n) for(int i = (int)n; i >= 1; i--)
#define Looprll1(i, n) for(ll i = (ll)n; i >= 1; i--)
#define Foreach(buf, container) for(auto buf : container)
#define Loopdiag(i, j, h, w, sum) for(int i = ((sum) >= (h) ? (h) - 1 : (sum)), j = (sum) - i; i >= 0 && j < (w); i--, j++)
#define Loopdiagr(i, j, h, w, sum) for(int j = ((sum) >= (w) ? (w) - 1 : (sum)), i = (sum) - j; j >= 0 && i < (h); j--, i++)
#define Loopdiagsym(i, j, h, w, gap) for (int i = ((gap) >= 0 ? (gap) : 0), j = i - (gap); i < (h) && j < (w); i++, j++)
#define Loopdiagsymr(i, j, h, w, gap) for (int i = ((gap) > (h) - (w) - 1 ? (h) - 1 : (w) - 1 + (gap)), j = i - (gap); i >= 0 && j >= 0; i--, j--)
#define Loopitr(itr, container) for(auto itr = container.begin(); itr != container.end(); itr++)
#define printv(vector) Loop(ex_i, vector.size()) { cout << vector[ex_i] << " "; } cout << endl;
#define printmx(matrix) Loop(ex_i, matrix.size()) { Loop(ex_j, matrix[ex_i].size()) { cout << matrix[ex_i][ex_j] << " "; } cout << endl; }
#define quickio() ios::sync_with_stdio(false); cin.tie(0);
#define bitmanip(m,val) static_cast<bitset<(int)m>>(val)
#define Comp(type_t) bool operator<(const type_t &another) const
#define fst first
#define snd second
bool nearlyeq(double x, double y) { return abs(x - y) < eps; }
bool inrange(ll x, ll t) { return x >= 0 && x < t; }
bool inrange(vll xs, ll t) { Foreach(x, xs) if (!(x >= 0 && x < t)) return false; return true; }
int ceillog2(ll x) { int ret = 0;	x--; while (x > 0) { ret++; x >>= 1; } return ret; }
ll rndf(double x) { return (ll)(x + (x >= 0 ? 0.5 : -0.5)); }
ll floorsqrt(ll x) { ll m = (ll)sqrt((double)x); return m + (m * m <= x ? 0 : -1); }
ll ceilsqrt(ll x) { ll m = (ll)sqrt((double)x); return m + (x <= m * m ? 0 : 1); }
ll rnddiv(ll a, ll b) { return (a / b + (a % b * 2 >= b ? 1 : 0)); }
ll ceildiv(ll a, ll b) { return (a / b + (a % b == 0 ? 0 : 1)); }
ll gcd(ll m, ll n) { if (n == 0) return m; else return gcd(n, m % n); }
ll lcm(ll m, ll n) { return m * n / gcd(m, n); }

/*******************************************************/

// range = [l, r), return last value causing "t" in evalfunc that returns l->[t,...,t,f,...,f)->r
// NOTE: if [f,...,f) then return l - 1, if [l, r) = empty set then invalid use
template<typename val_t, typename bsargv_t>
val_t lower_binary_search(val_t l, val_t r, const bsargv_t &v, bool(*evalfunc)(val_t, const bsargv_t&)) {
	if (r - l == 1) {
		if (evalfunc(l, v)) return l;
		else return l - 1;
	}
	val_t m = (l + r) / 2;
	if (evalfunc(m, v)) return lower_binary_search<val_t, bsargv_t>(m, r, v, evalfunc);
	else return lower_binary_search<val_t, bsargv_t>(l, m, v, evalfunc);
}

// range = [l, r), return first value causing "t" in evalfunc that returns l->[f,...,f,t,...,t)->r
// NOTE: if [f,...,f) then return r, if [l, r) = empty set then invalid use
template<typename val_t, typename bsargv_t>
val_t upper_binary_search(val_t l, val_t r, const bsargv_t &v, bool(*evalfunc)(val_t, const bsargv_t&)) {
	if (r - l == 1) {
		if (evalfunc(l, v)) return l;
		else return r;
	}
	val_t m = (l + r) / 2;
	if (evalfunc(m, v)) return upper_binary_search<val_t, bsargv_t>(l, m, v, evalfunc);
	else return upper_binary_search<val_t, bsargv_t>(m, r, v, evalfunc);
}

struct bsargv_t {
	int n, q;
	string s;
	vector<char> c, d;
};

bool evalfunc_l(int val, const bsargv_t &v) {
	Loop(i, v.q) {
		if (v.s[val] == v.c[i]) {
			if (v.d[i] == 'L') {
				val--;
			}
			else {
				val++;
			}
			if (val < 0) return false;
			if (val >= v.n) return true;
		}
	}
	return true;
}


bool evalfunc_r(int val, const bsargv_t &v) {
	Loop(i, v.q) {
		if (v.s[val] == v.c[i]) {
			if (v.d[i] == 'L') {
				val--;
			}
			else {
				val++;
			}
			if (val < 0) return true;
			if (val >= v.n) return false;
		}
	}
	return true;
}

int main() {
	int n, q; cin >> n >> q;
	string s; cin >> s;
	vector<char> c(q), d(q);
	Loop(i, q) {
		cin >> c[i] >> d[i];
	}
	bsargv_t v = { n, q, s, c, d };
	int l = upper_binary_search(0, n, v, evalfunc_l);
	int r = lower_binary_search(0, n, v, evalfunc_r);
	cout << max(0, r - l + 1) << endl;
}

Measured memory_bytes: 1412