#[allow(unused_imports)]
use std::cmp::{Ordering};

#[allow(unused_imports)]
use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, VecDeque};

#[allow(unused_imports)]
use std::io::{stdin, stdout, BufWriter, Write};

#[allow(unused_imports)]
use std::iter::FromIterator;

#[allow(unused_macros)]
macro_rules! min {
    ($x: expr) => ($x);
    ($x: expr, $($z: expr),+) => {{
        std::cmp::min($x, min!($($z),*))
    }}
}

#[allow(unused_macros)]
macro_rules! max {
    ($x: expr) => ($x);
    ($x: expr, $($z: expr),+) => {{
        std::cmp::max($x, max!($($z),*))
    }}
}

#[allow(unused_macros)]
macro_rules! get { 
    ([$t: ty]) => { 
        { 
            let mut line = String::new(); 
            stdin().read_line(&mut line).unwrap(); 
            line.split_whitespace().map(|t|t.parse::<$t>().unwrap()).collect::<Vec<_>>()
        }
    };
    ([$t: ty];$n: expr) => {
        (0..$n).map(|_|get!([$t])).collect::<Vec<_>>()
    };
    ($t: ty) => {
        {
            let mut line = String::new();
            stdin().read_line(&mut line).unwrap();
            line.trim().parse::<$t>().unwrap()
        }
    };
    ($($t: ty),*) => {
        { 
            let mut line = String::new();
            stdin().read_line(&mut line).unwrap();
            let mut iter = line.split_whitespace();
            ($(iter.next().unwrap().parse::<$t>().unwrap(),)*)
        }
    };
    ($t: ty; $n: expr) => {
        (0..$n).map(|_|get!($t)).collect::<Vec<_>>()
    };
    ($($t: ty),*; $n: expr) => {
        (0..$n).map(|_|get!($($t),*)).collect::<Vec<_>>()
    };
}

#[allow(unused_macros)]
macro_rules! debug {
    ($($a:expr),*) => {
        #[cfg(debug_assertions)]
        writeln!(&mut std::io::stderr(), concat!("[DEBUG] ", $(stringify!($a), "={:?} "),*), $($a),*).unwrap();
    }
}

const BIG_STACK_SIZE: bool = true;

#[allow(dead_code)]
fn main() {
    use std::thread;
    if BIG_STACK_SIZE {
        thread::Builder::new()
            .stack_size(32 * 1024 * 1024)
            .name("solve".into())
            .spawn(solve)
            .unwrap()
            .join()
            .unwrap();
    } else {
        solve();
    }
}

fn solve() {
    let (n, q) = get!(usize, usize);
    let s = get!(String).chars().collect::<Vec<_>>();
    let tdt = get!(String, String; q);
    let mut td = Vec::new();
    for (t, d) in tdt {
        td.push((t.into_bytes()[0] as char, d.into_bytes()[0] as char));
    }

    if n == 1 {
        for (t,_d) in td {
            if t == s[0] {
                println!("0");
                return;
            }
        }
        println!("1");
        return;
    }

    let mut count = 0;

    let mut l = 0;
    let mut r = n+1;
    while l < r {
        let mid = (l+r)/2;
        let mut po = mid;
        for &(t,d) in td.iter() {
            if po == 0 || po == n+1 {
                break;
            }
            if s[po-1] == t {
                if d == 'L' {
                    po -= 1;
                } else {
                    po += 1;
                }
            }
        }
        if po == 0 {
            if l == mid {
                break;
            }
            l = mid;
        } else {
            r = mid;
        }
    }
    debug!(l);
    if r != 0 && r != n+1 {
        count += l;
    }

    let mut l = 0;
    let mut r = n+1;
    while l < r {
        let mid = (l+r)/2;
        let mut po = mid;
        for &(t,d) in td.iter() {
            if po == 0 || po == n+1 {
                break;
            }
            if s[po-1] == t {
                if d == 'L' {
                    po -= 1;
                } else {
                    po += 1;
                }
            }
        }
        if po == n+1 {
            r = mid;
        } else {
            if l == mid {
                break;
            }
            l = mid;
        }
    }
    debug!(l);
    if r != 0 && r != n+1 {
        count += n-l;
    }

    println!("{}", n-min!(n, count));

}
