#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;
#define pb push_back
#define mp make_pair
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define lb lower_bound
#define ub upper_bound
#define sz(v) int((v).size())
#define do_not_disturb ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define endl '\n'
void solve() {
int n, m;
cin >> n >> m;
vector <pii> v(n);
vector <int> c(m);
for (auto &to : v) cin >> to.second >> to.first;
for (auto &to : c) cin >> to;
int j = 0;
sort(rall(v));
sort(rall(c));
for (int i = 0; i < n; i++) {
if (j < m && c[j] >= v[i].second) {
j++;
}
}
cout << j;
}
int main() {
do_not_disturb
int t = 1;
//~ cin >> t;
while (t--) {
solve();
}
return 0;
}
