#include <bits/stdc++.h>
using namespace std;
int main(){
long long n,m,t1,t2;
cin>>n>>m;
vector <pair<long long,long long>> v1;
vector <long long> v2;
//vector <pair<pair<long long,long long>,long long>> v3;
for (long long i=0; i<n; i++){
cin>>t1>>t2;
v1.push_back({t2,t1});
}
sort(v1.begin(),v1.end());
for (long long i=0; i<m; i++){
cin>>t1;
v2.push_back(t1);
}
sort(v2.begin(),v2.end());
long long l=0;
long long r=min(m,n);
long long mid;
while (r>l){
mid=(r+l+1)/2;
t1=m-mid;
for (int i=0; i<n; i++){
if (v1[i].first <= v2[t1]){
t1++;
if (t1==m) {break;}
}
}
if (t1==m){l=mid;}
else {r=mid-1;}
}
cout<<r;
}
