#include "bits/stdc++.h"
#define fast ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define ll long long
#define pb push_back
#define in insert
#define F first
#define S second
#define vll vector<ll>
#define all(v) v.begin(),v.end()
#define endl '\n'
#define pii pair<ll,ll>
#define yes cout << "YES" << endl;
#define no cout << "NO" << endl;
using namespace std;
const ll INF = 1e18, mod = 1e9 + 7, N = 2e5 + 5;
ll gcd(ll a, ll b) {
if (b == 0) {
return a;
}
return gcd(b, a % b);
}
ll lcm(ll a, ll b) {
return (a / gcd(a, b)) * b;
}
void solve() {
ll n, m;
cin >> n >> m;
vector<pii> v;
ll x, y;
for (int i = 0; i < n; i++) {
cin >> x >> y;
v.pb({y, x});
}
vector<ll> f;
ll r;
for (int i = 0; i < m; i++) {
cin >> r;
f.pb(r);
}
sort(all(f));
sort(all(v));
ll cnt = 0;
set<ll> used;
ll in = -1;
ll j =0;
for (ll i = 0; i < m; i++) {
while (j < v.size() && v[j].first < f[i]) {
j++;
}
if (j == v.size()) break;
cnt++;
j++;
}
cout << cnt << endl;
}
int main() {
fast;
ll t = 1;
// cin >> t;
while (t--) {
solve();
}
return 0;
}
