#include <bits/stdc++.h>
using namespace std;
const int N=200010;
struct node {
    int l,r;
} a[N];
int n,m,t[N],flag[N],ret=0;
int cmd(node x,node y)
{
    if (x.r==y.r)
    {
        return x.l<y.l;
    }
    return x.r<y.r;
}
int main() {
    freopen("dream.in","r",stdin);
    freopen("dream.out","w",stdout);
    scanf("%d%d",&n,&m);
    for (int i=1;i<=n;i++)
    {
        scanf("%d%d",&a[i].l,&a[i].r);
    }  
    for (int i=1;i<=m;i++)
    {
        scanf("%d",&t[i]);
    }
    sort(a+1,a+n+1,cmd);
    sort(t+1,t+m+1);
    for (int i=1;i<=n;i++)
    {
        for (int j=1;j<=m;j++)
        {
           if (!flag[i] && a[i].l<=t[j] && t[j]<=a[i].r)
           {
               ret++;
               flag[i]=1;
               continue;
           }
        }
    }
    printf("%d",ret);
}