#include<bits/stdc++.h>
using namespace std;
struct A
{
    long long st,ed;
} a[200010];
bool srt(A a,A b)
{
    return a.st<=b.st? true:false;
}
long long b[200010];
long long l=1,r=1,tot;
int main()
{
    freopen("dream.in","r",stdin);
    freopen("dream.out","w",stdout);
    int m,n;
    cin>>n>>m;
    for(int i=1;i<=n;i++) cin>>a[i].st>>a[i].ed;
    for(int i=1;i<=m;i++) cin>>b[i];
    sort(a+1,a+n+1,srt); 
    sort(b+1,b+m+1);
    for(int i=1;i<=n;i++)
    {
        int j=l;r=j+1;
        while(b[j]<a[i].st&&b[j]!=0&&j<=m)
        {
            j=r;
            r++;
        }
        if(b[j]>=a[i].st&&b[j]<=a[i].ed) 
        {
            tot++;
            b[j]=0;
            j=r;
            r++;
        }
        l=j;
    }
    cout<<tot<<endl;
    return 0;
}