#include <bits/stdc++.h>
using namespace std;
#define int long long
#define INF (int)1e18
#define f first
#define s second
mt19937_64 RNG(chrono::steady_clock::now().time_since_epoch().count());
int n, m;
vector <int> c;
vector <pair<int, int>> a;
bool check(int y){
int dp = 0;
for (auto x : a){
int num = c.end() - lower_bound(c.begin(), c.end(), x.s);
if (num >= y - dp) dp++;
}
return dp >= y;
}
void Solve()
{
cin >> n >> m;
a.resize(n);
c.resize(m);
for (auto &x : a) cin >> x.s >> x.f;
sort(a.begin(), a.end());
for (auto &x : c) cin >> x;
sort(c.begin(), c.end());
int l = 0, r = n;
while (l != r){
int mid = (l + r + 1) / 2;
if (check(mid)) l = mid;
else r = mid - 1;
}
cout << l << "\n";
}
int32_t main()
{
auto begin = std::chrono::high_resolution_clock::now();
ios_base::sync_with_stdio(0);
cin.tie(0);
int t = 1;
// cin >> t;
for(int i = 1; i <= t; i++)
{
//cout << "Case #" << i << ": ";
Solve();
}
auto end = std::chrono::high_resolution_clock::now();
auto elapsed = std::chrono::duration_cast<std::chrono::nanoseconds>(end - begin);
cerr << "Time measured: " << elapsed.count() * 1e-9 << " seconds.\n";
return 0;
}
