#include <bits/stdc++.h>
using namespace std;
using pll = pair<long long, long long>;
#define ll long long
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define pb push_back
#define eb emplace_back
#define f first
#define s second
template<typename A, typename B> ostream& operator<<(ostream &os, const pair<A, B> &p) { return os << '(' << p.first << ", " << p.second << ')'; }
template<typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type> ostream& operator<<(ostream &os, const T_container &v) { os << '{'; string sep; for (const T &x : v) os << sep << x, sep = ", "; return os << '}'; }
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0200r0.html
template<class Fun> class y_combinator_result {
Fun fun_;
public:
template<class T> explicit y_combinator_result(T &&fun): fun_(std::forward<T>(fun)) {}
template<class ...Args> decltype(auto) operator()(Args &&...args) { return fun_(std::ref(*this), std::forward<Args>(args)...); }
};
template<class Fun> decltype(auto) y_combinator(Fun &&fun) { return y_combinator_result<std::decay_t<Fun>>(std::forward<Fun>(fun)); }
#ifdef I_AM_NOOB
#define gg(...) [](const auto&...x){ char c='='; cerr<<#__VA_ARGS__; ((cerr<<exchange(c,',')<<x),...); cerr<<endl; }(__VA_ARGS__);
#else
#define gg(...) 777771449
#endif
constexpr ll INFF = 1e18;
constexpr ll P = 1e9+7;
// constexpr ll P = 998244353;
int main() {
cin.tie(0) -> ios::sync_with_stdio(0);
ll n, m; while (cin >> n >> m) {
vector<pll> a(n+1);
for (ll i = 1; i <= n; i++) {
cin >> a[i].s >> a[i].f;
}
sort(all(a));
vector<ll> frames(m+1);
for (ll i = 1; i <= m; i++) {
cin >> frames[i];
}
sort(all(frames));
ll ans = 0;
ll j = n;
for (ll i = m; i >= 1; i--) {
while (j > 0 && a[j].s > frames[i]) j--;
if (j == 0) break;
ans++;
j--;
if (j == 0) break;
}
cout << ans << endl;
}
return 0;
}
