#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define ordered_set <int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
#define ordered_multiset <int, null_type, less_equal <int>, rb_tree_tag, tree_order_statistics_node_update>
#define int long long
#define double long double
#define pii pair <int, int>
#define tiii tuple <int, int, int>
#define tiiii tuple <int, int, int, int>
#define emb emplace_back
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define iShowSpeed cin.tie(NULL)->sync_with_stdio(false)
#define matrix vector <vector <int>>
#define mat(n, m) vector <vector <int>> (n, vector <int> (m));
const int mod = 1e9 + 7;
const int inf = 1e18;
const matrix II = {{1, 0}, {0, 1}};
const int N = 1e5 + 5;
pii fenwick[N];
void update(pii val, int idx){
while (idx < N) fenwick[idx] = max(fenwick[idx], val), idx += idx & -idx;
}
pii query(int idx){
pii mx = {0, 0};
while (idx > 0) mx = max(mx, fenwick[idx]), idx -= idx & -idx;
return mx;
}
void solve(){
int n, m; cin >> n >> m;
vector <pii> a(n + 1);
vector <int> b(m + 1);
for (int i = 1; i <= n; i++) cin >> a[i].second >> a[i].first;
for (int i = 1; i <= m; i++) cin >> b[i];
sort(all(a)), sort(all(b));
int idx = m;
int ans = 0;
for (int i = n; i >= 1; i--) {
auto [val, sz] = a[i];
if (idx >= 1 && sz <= b[idx]) ans++, idx--;
}
cout << ans;
}
int32_t main(){
iShowSpeed;
// int q; cin >> q; while (q--)
solve();
}
