#include <bits/stdc++.h>
using namespace std;
void testCase() {
int n, m;
cin >> n >> m;
vector<pair<int, int>> a(n);
for (auto &it : a) {
cin >> it.second >> it.first;
}
sort(a.begin(), a.end());
vector<int> b(m);
for (int &x : b) {
cin >> x;
}
sort(b.rbegin(), b.rend());
int ans = 0;
for (int x : b) {
while (!a.empty() && x < a.back().second) {
a.pop_back();
}
if (a.empty()) {
break;
}
ans += 1;
a.pop_back();
}
cout << ans << '\n';
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int tests = 1;
for (int tc = 0; tc < tests; ++tc) {
testCase();
}
return 0;
}
