#include<iostream>
#include<algorithm>
#include<cstdio>
using namespace std;
const int MAXN=200005;
int n,m;
long long ans;
struct dream{
    long long l;
    long long r;
    bool flag;
}d[MAXN];
struct time{
    long long t;
    bool tb;
}ti[MAXN];
bool cmp1(dream a,dream b){
    if(a.l==b.l){
        return a.r<b.r;
    }else
    return a.l<b.l;
}
bool cmp2(time a,time b){
    return a.t<b.t;
}
int main(){
    freopen("dream.in","r",stdin);
    freopen("dream.out","w",stdout);
    cin>>n>>m;
    for(int i=1;i<=n;i++){
        cin>>d[i].l>>d[i].r;
    }
    for(int i=1;i<=m;i++){
        cin>>ti[i].t;
    }
    int k=1;;
    sort(d+1,d+1+n,cmp1);
    sort(ti+1,ti+1+n,cmp2);
    for(int i=1;i<=n;i++){
        for(int j=k;j<=m;j++){
            if(ti[j].t>=d[i].l&&ti[j].t<=d[i].r&&!d[i].flag&&!ti[j].tb){
                ans++;
                d[i].flag=1;
                ti[j].tb=1;
                k++;
                break;
            }
        }
            
        
    }
    cout<<ans<<endl;
    return 0;
}