#include<iostream>
#include<algorithm>
#include<cstdio>
using namespace std;
struct xs
{
	int l,r;
};
xs we[200001];
int p[200001];
int n,m,ans=0,head=1;
bool cmp1(xs a,xs b)
{
	if(a.l==b.l)
	return a.r<b.r;
	return a.l<b.l;
}
bool cmp2(int a,int b)
{
	return a<b;
}
int LINYIN()
{
	freopen("dream.in","r",stdin);
	freopen("dream.out","w",stdout);
	scanf("%d%d",&n,&m);
	for(register int i=1;i<=n;i++)
	{
		scanf("%d%d",&we[i].l,&we[i].r);
	}
	for(register int i=1;i<=m;i++)
	{
		scanf("%d",&p[i]);
	}
	sort(we+1,we+1+n,cmp1);
	sort(p+1,p+1+m,cmp2);
	for(register int i=1;i<=n;i++)
	{
		for(register int j=head;j<=m;j++)
		{
			if(we[i].l<=p[j]&&we[i].r>=p[j])
			{
				head=j+1;
				ans++;
				break;
			}
		}
	}
	printf("%d",ans);
	return 0;
}
int sdw=LINYIN();
int main()
{
	;
}