#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 1e5 + 5, inf = 2e9;
int n, m, c[N];
pair <int, int> p[N];
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
// freopen(".INP", "r", stdin);
// freopen(".OUT", "w", stdout);
cin >> n >> m;
for (int i=1;i<=n;++i) cin >> p[i].second >> p[i].first;
for (int i=1;i<=m;++i) cin >> c[i];
sort(p+1, p+n+1);
sort(c+1, c+m+1);
reverse(p+1, p+n+1);
reverse(c+1, c+m+1);
int cur = 1, ans = 0;
for (int i=1;i<=n;++i) {
if (cur == m + 1) break;
if (p[i].second <= c[cur]) cur++, ans++;
}
cout << ans;
}
