#include <bits/stdc++.h>
using namespace std;
using ll = long long;
ll INF = 1e18;
ll MOD = 1e9 + 7;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
ll n, m;
cin >> n >> m;
vector<pair<ll, ll>> s(n);
vector<ll> c(m);
for (ll i = 0; i < n; i++) {
cin >> s[i].second >> s[i].first;
}
sort(s.begin(), s.end());
for (ll i = 0; i < m; i++) {
cin >> c[i];
}
sort(c.rbegin(), c.rend());
ll cnt = 0;
for (ll i = n - 1; i >= 0; i--) {
if (cnt == m) {
break;
}
if (s[i].second <= c[cnt]) {
cnt++;
}
}
cout << cnt;
}
