#include<bits/stdc++.h>
using namespace std;
#define MAXN 4000005
#define ll long long
ll hd[MAXN],nxt[MAXN],ed[MAXN],used[MAXN];
ll s[MAXN];
//ll n,m,idx;
ll n,m,ans,x,idx;
struct node{
    ll l,r,st,num;
}line[MAXN];
bool cmp(node a,node b){
    return a.st<b.st;
}
void build(ll x,ll y){
    nxt[++idx]=hd[x];
    hd[x]=idx;
    ed[idx]=y;
}
int main(){
        freopen("dream.in","r",stdin);
        freopen("dream.out","w",stdout);
    cin>>n>>m;
    for(int i=1;i<=n;i++){
        cin>>line[i].l>>line[i].r;line[i].num=i;
    }
    for(int i=1;i<=m;i++){
        cin>>x;
        for(int j=1;j<=n;j++){
            if(x<=line[j].r&&x>=line[j].l){
//                cout<<i<<" "<<j<<" "<<s[i]<<endl;
                build(j,i);
                s[i]++;
                line[j].st++;
            }
        }
    }
    sort(line+1,line+1+n,cmp);
    for(int i=1;i<=n;i++){
        int cnt=1e9,k=0,num=0;
//        cout<<i<<endl;
        for(int j=hd[line[i].num];j;j=nxt[j]){
            int y=ed[j];
//            cout<<i<<" "<<y<<" "<<s[y]<<endl;
            if(!used[y]){
                k=1;
                if(s[y]<cnt){
                    cnt=s[y];
                    num=y;
                }
                s[y]--;
            }
        }
        if(k){
            ans++;
            used[cnt]=1;
        }
    }
    cout<<ans;
    return 0;
}