#include <bits/stdc++.h>

using namespace std;
using ll = long long;

#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
#define pb push_back
#define ff first
#define sc second

signed main() {
    ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);

    int n, m; cin >> n >> m;
    vector<pair<int, int>> a(n);
    vector<int> b(m);
    for (int i = 0; i < n; i++) cin >>a[i].ff >> a[i].sc;
    for (int i = 0; i < m; i++) cin >> b[i];
    sort(all(a), [&](pair<int, int> x, pair<int, int> y) {return (x.sc == y.sc ? x.ff < y.ff : x.sc < y.sc); });
    sort(all(b));
    int ans = 0, ua = n - 1, ub = m - 1;
    while (ua >= 0 && ub >= 0) {
        if (a[ua].ff <= b[ub]) {
            ans++;
            ua--; ub--;
        } else ua--;
    }
    cout << ans << '\n';

    return 0;
}