#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=2010;
int n,m,cnt=1,res,b[N];
ll t[N];
vector<int>v[N];
struct node {
    ll l,r;
}a[N];
bool cmp (node x,node y) {
    if (x.l==y.l) return x.r<y.r;
    return x.l<y.l;
} 
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+1+n,cmp);
    sort(t+1,t+1+m);
    for (int i=1;i<=m;i++) {
        for (int j=1;j<=n;j++) {
            if (t[i]<a[j].l) break;
            if (t[i]<=a[j].r) {
                b[i]++;
                v[j].push_back(i);
            }
        }
    }
    for (int i=1;i<=n;i++) {
        if (v[i].size()==0) continue;
        sort(v[i].begin(),v[i].end()); 
        if (b[v[i][0]]>0) res++;
        for (int j=0;j<v[i].size();j++) {
            b[v[i][j]]--;
        }
    }
    cout << res <<endl;
    return 0; 
}