#include <bits/stdc++.h>
#include <experimental/random>
#include <random>
//#include <ext/pb_ds/assoc_container.hpp>
//using namespace __gnu_pbds;
using namespace std;
using ld = long double;
using ll = long long;
const ll INF = 3e18, MOD = 1e9 + 7;
void solve();
signed main() {
#ifdef LOCAL
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
ios::sync_with_stdio(false);
cin.tie(0);
int q = 1;
//cin >> q;
while (q--) {
solve();
}
}
void solve() {
ll n, m; cin >> n >> m;
vector<pair<ll, ll>> a(n);
for (int i = 0; i < n; i++) {
cin >> a[i].second >> a[i].first;
}
vector<ll> c(m);
for (int i = 0; i < m; i++) {
cin >> c[i];
}
sort(a.rbegin(), a.rend());
sort(c.rbegin(), c.rend());
ll id = 0, ans = 0;
for (auto x : c) {
while (id < n && a[id].second > x) {
id++;
}
if (id == n) break;
ans++; id++;
}
cout << ans;
}
