#include <bits/stdc++.h>
using namespace std;
vector<pair<int,int> > slike;
vector<int> ramovi;
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int n,m;
cin>>n>>m;
slike.resize(n);
for(int i=0;i<n;i++) cin>>slike[i].second>>slike[i].first;
sort(slike.begin(),slike.end());
ramovi.resize(m);
for(int i=0;i<m;i++) cin>>ramovi[i];
sort(ramovi.begin(),ramovi.end());
int kolko=0;
int p1=n-1,p2=m-1;
while(p1>=0 && p2>=0)
{
if(ramovi[p2]>=slike[p1].second)
{
p2--;
kolko++;
}
p1--;
}
cout<<kolko<<endl;
}
