
package main

import (
	"bufio"
	"os"
	"strconv"
	"strings"
	"fmt"
)

type TupleInt struct {
	first  int
	second int
}

func main() {
	sc := NewScanner()
	N,Q,s := sc.NextInt(),sc.NextInt(),sc.Next()

	golem := make([]int,N)
	for i, _ := range golem {
		golem[i] = 1
	}

	slice := strings.Split(s, "")

	for i:=0; i<Q; i++ {
		t,d := sc.Next(),sc.Next()
		if d=="R" {
			for i,s := range slice{
				if i==N-1 {
					if s==t {
						golem[i] = 0
					}
				} else {
					if s==t {
						golem[i+1] = golem[i+1] + golem[i]
						golem[i] = 0
					}
				}
			}
		} else {
			for i,s := range slice{
				if i==0 {
					if s==t {
						golem[i] = 0
					}
				} else {
					if s==t {
						golem[i-1] = golem[i-1] + golem[i]
						golem[i] = 0
					}
				}
			}
		}
	}

	total := 0
	for _, n := range golem {
		total = total + n
	}
	fmt.Println(total)







}
func min(a int, b int) int {
	if a < b {
		return a
	}
	return b
}

func Max(a int, b int) int {
	if a < b {
		return b
	}
	return a
}

type SortInterFace []TupleInt

func (s SortInterFace) Len() int {
	return len(s)
}
func (s SortInterFace) Less(i, j int) bool {
	return s[i].first < s[j].first
}
func (s SortInterFace) Swap(i, j int) {
	s[i], s[j] = s[j], s[i]
}

type Scanner struct {
	r   *bufio.Reader
	buf []byte
	p   int
}

func NewScanner() *Scanner {
	rdr := bufio.NewReaderSize(os.Stdin, 1000)
	return &Scanner{r: rdr}
}
func (s *Scanner) Next() string {
	s.pre()
	start := s.p
	for ; s.p < len(s.buf); s.p++ {
		if s.buf[s.p] == ' ' {
			break
		}
	}
	result := string(s.buf[start:s.p])
	s.p++
	return result
}
func (s *Scanner) NextLine() string {
	s.pre()
	start := s.p
	s.p = len(s.buf)
	return string(s.buf[start:])
}
func (s *Scanner) NextInt() int {
	v, _ := strconv.Atoi(s.Next())
	return v
}
func (s *Scanner) NextInt64() int64 {
	v, _ := strconv.ParseInt(s.Next(), 10, 64)
	return v
}

func (s *Scanner) NextFloat() float64 {
	v, _ := strconv.ParseFloat(s.Next(), 64)
	return v
}

func (s *Scanner) NextIntArray() []int {
	s.pre()
	start := s.p
	result := []int{}
	for ; s.p < len(s.buf)+1; s.p++ {
		if s.p == len(s.buf) || s.buf[s.p] == ' ' {
			v, _ := strconv.ParseInt(string(s.buf[start:s.p]), 10, 0)
			result = append(result, int(v))
			start = s.p + 1
		}
	}

	return result
}
func (s *Scanner) NextInt64Array() []int64 {
	s.pre()
	start := s.p
	result := []int64{}
	for ; s.p < len(s.buf)+1; s.p++ {
		if s.p == len(s.buf) || s.buf[s.p] == ' ' {
			v, _ := strconv.ParseInt(string(s.buf[start:s.p]), 10, 64)
			result = append(result, v)
			start = s.p + 1
		}
	}
	return result
}

func (s *Scanner) NextMap() map[int]bool {
	s.pre()
	start := s.p
	mp := map[int]bool{}
	for ; s.p < len(s.buf); s.p++ {
		if s.buf[s.p] == ' ' {
			v, _ := strconv.Atoi(string(s.buf[start:s.p]))
			mp[v] = true
			start = s.p + 1
		}
	}
	v, _ := strconv.Atoi(string(s.buf[start:s.p]))
	mp[v] = true

	return mp
}

func (s *Scanner) pre() {
	if s.p >= len(s.buf) {
		s.readLine()
		s.p = 0
	}
}
func (s *Scanner) readLine() {
	s.buf = make([]byte, 0)
	for {
		l, p, e := s.r.ReadLine()
		if e != nil {
			panic(e)
		}
		s.buf = append(s.buf, l...)
		if !p {
			break
		}
	}
}

