#include <bits/stdc++.h>
using namespace std;
#define ll long long
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
int n, m;
cin >> n >> m;
vector<pair<int, int>> p (n);
for (int i = 0; i < n; i++) {
cin >> p[i].second >> p[i].first;
}
vector<int> c (m, 0);
for (int i = 0; i < m; i++) {
cin >> c[i];
}
sort(p.begin(), p.end(), greater<pair<int, int>>());
sort(c.begin(), c.end(), greater<int>());
int in = 0;
for (int i = 0; i < n; i++) {
if (in < m && p[i].second <= c[in]) {
in++;
}
}
cout << in << '\n';
}
