#include <bits/stdc++.h>
#define int long long
#define vi vector<int>
#define ii pair<int, int>
#define f first
#define s second
#define all(x) (x).begin(), (x).end()
#define P 31
#define mod 1'000'000'007
#define inf 1'000'000'000'000
#define pb push_back
#define str string
#define sz(x) (x).size()
#define vvi vector<vi>
#define fun function
#define oopt cin.tie(0);cout.tie(0);ios_base::sync_with_stdio(false);
#define file freopen("problemname.in", "r", stdin); freopen("pr.out", "w", stdout);
#define dbg(v) cout << "Line(" << __LINE__ << ") -> " << #v << " = " << (v) << endl;
using namespace std;
template <class T, int SZ> using arr = array<T, SZ>;
struct slika
{
int vl, vr;
};
slika a[200005];
int b[200005];
int opcije[200005];
signed main()
{
oopt;
int n, m;
cin >> n >> m;
for (int i = 0; i < n; i++)
cin >> a[i].vl >> a[i].vr;
sort(a, a+n, [](slika&p, slika&d){
if (p.vr == d.vr)
return p.vl < d.vl;
return p.vr < d.vr;
});
// cout << m << "\n";
for (int i = 0; i < m; i++)
cin >> b[i];
sort(b, b+m);
int rez = 0;
for (int i = n-1; i >= 0 && rez < m; i--)
{
if (b[m-rez-1] >= a[i].vl)
rez++;
}
cout << rez << "\n";
return 0;
}
