TRAINING

#define task "TRAINING"
#include <iostream>
#include <cstdio>

using namespace std;

using ll = long long;
using ld = long double;

constexpr int N = 2e5 + 5;

int n, q;
string s;

char t[N], c[N];

void Read()
{
    cin >> n >> q >> s;
    s = " " + s;

    for (int i = 1; i <= q; ++i)
        cin >> c[i] >> t[i];
}

bool Check_0(int pos)
{
    for (int i = 1; i <= q; ++i)
    {
        if (c[i] == s[pos])
        {
            if (t[i] == 'L')
                --pos;
            else
                ++pos;
        }

        if (pos == 0)
            return true;
        else if (pos == n + 1)
            return false;
    }

    return false;
}

bool Check_1(int pos)
{
    for (int i = 1; i <= q; ++i)
    {
        if (c[i] == s[pos])
        {
            if (t[i] == 'L')
                --pos;
            else
                ++pos;
        }

        if (pos == 0)
            return false;
        else if (pos == n + 1)
            return true;
    }

    return false;
}

void Solve()
{
    int l = 1, m, h = n;
    int ans(0);

    while (l <= h)
    {
        m = (l + h) / 2;
        if (Check_0(m))
            l = m + 1;
        else
            h = m - 1;
    }

    ans = h;

    l = 1, h = n;

    while (l <= h)
    {
        m = (l + h) / 2;
        if (Check_1(m))
            h = m - 1;
        else
            l = m + 1;
    }

    ans += n - h;

    cout << n - ans;
}

int32_t main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    if (fopen(task ".INP", "r"))
    {
        freopen(task ".INP", "r", stdin);
        freopen(task ".OUT", "w", stdout);
    }

    Read();
    Solve();
}