#include <bits/stdc++.h>
#define ll long long
#define mod 1000000007
#define INF 1000000000
using namespace std;
int main(){
int n, m, s, v;
cin>>n>>m;
vector<vector<int>> so;
vector<int> ra;
for (int i = 1; i <= n; i++){
cin>>s>>v;
so.push_back({v, s});
}
for (int i = 1; i <= m; i++){
cin>>s;
ra.push_back(s);
}
sort(so.begin(), so.end());
reverse(so.begin(), so.end());
sort(ra.begin(), ra.end());
reverse(ra.begin(), ra.end());
int cur = 0, ans = 0;
for (int i = 0; i < n; i++){
if (cur < m && so[i][1] <= ra[cur]){
cur++, ans++;
}
}
cout<<ans;
}
