#include <bits/stdc++.h>
#define int long long
using namespace std;
int a,b;
int z[1000005];
multiset<int> s;
priority_queue<pair<int,int>> q;
bool cmp(pair<int,int> a,pair<int,int> b){
return a.second<b.second;
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> a >> b;
for (int i=1;i<=a;i++){
int x,y;
cin >> x >> y;
q.push({y,x});
}
for (int i=1;i<=b;i++){
cin >> z[i];
}
sort(z+1,z+1+b);
int ans=0;
for (int i=b;i>=1;i--){
while (q.size() && q.top().second>z[i]){
q.pop();
}
if (q.size()){
ans++;
q.pop();
}else{
break;
}
}
cout << ans << " ";
return 0;
}
