#include<bits/stdc++.h>
using namespace std;
const int N=2e5+5,YL=1e9+7;
inline int MO(const int &x){return x>=YL?x-YL:x;}
inline int in(){int k;cin>>k;return k;}
inline int low(int x){return x&(-x);}
char s[N],a[N],b[N];int n,m;
typedef std::pair<int,int> P;
#define mk make_pair
inline void add(int &x,int y){if((x+=y)>=YL)x-=YL;}
int check(int mid)
{
	int p=mid;
	for(int i=1;i<=m;++i)
		if(s[p]==a[i])
		{
			p+=b[i]=='L'?-1:1;
			if(!p)return -1;
			else if(p>n)return 1;
		}
	return 0;
}
int main()
{
	ios::sync_with_stdio(0);
	cin>>n>>m>>s+1;
	for(int i=1;i<=m;++i)cin>>a[i]>>b[i];
	int l=1,r=n,ans=0;
	while(l<=r)
	{
		int mid=l+r>>1;
		if(check(mid)==-1)ans=mid,l=mid+1;
		else r=mid-1;
	}
	int res=n-ans;l=1,r=n,ans=n+1;
	while(l<=r)
	{
		int mid=l+r>>1;
		if(check(mid)== 1)ans=mid,r=mid-1;
		else l=mid+1;
	}
	res-=n-ans+1;printf("%d\n",res);
	return 0;
}
