#include<bits/stdc++.h>
using namespace std;
#define LL long long
#define pa pair<int,int>
const int Maxn=200010;
const int inf=2147483647;
int read()
{
	int x=0,f=1;char ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
	while(ch>='0'&&ch<='9')x=(x<<3)+(x<<1)+(ch^48),ch=getchar();
	return x*f;
}
int n,m,a[Maxn],b[Maxn];
char s[Maxn],s1[3],s2[3];
int g(int x)
{
	int p=x;
	for(int i=1;i<=m;i++)
	{
		if(a[i]==s[p]-'A')p+=b[i];
		if(p==0||p==n+1)return p;
	}
	return p;
}
int main()
{
	n=read(),m=read();
	scanf("%s",s+1);
	for(int i=1;i<=m;i++)
	{
		scanf("%s%s",s1,s2);
		a[i]=s1[0]-'A';b[i]=((s2[0]=='L')?-1:1);
	}
	int ans=n;
	int l=1,r=n;
	while(l<=r)
	{
		int mid=l+r>>1;
		if(g(mid)==0)l=mid+1;
		else r=mid-1;
	}
	ans-=(l-1);//printf("%d\n",l-1);
	l=1,r=n;
	while(l<=r)
	{
		int mid=l+r>>1;
		if(g(mid)==n+1)r=mid-1;
		else l=mid+1;
	}
	ans-=(n-r);//printf("%d",r+1);
	printf("%d",ans);
}