#include <algorithm>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <string>
#include <vector>
using namespace std;
typedef long long ll;
signed main() {
cin.tie(0)->sync_with_stdio(0);
int n, m;
cin >> n >> m;
vector<pair<int, int>> pics(n);
vector<int> frames(m);
for (auto &p : pics)
cin >> p.second >> p.first;
for (int &i : frames)
cin >> i;
sort(pics.begin(), pics.end());
sort(frames.begin(), frames.end());
int res = 0;
int i = n - 1, j = m - 1;
while (i > 0 && j > 0) {
if (frames[j] >= pics[i].second) {
++res;
--j;
}
--i;
}
cout << res << '\n';
}
