#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define fi first
#define se second
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n, m, x, ind = 0;
cin >> n >> m;
vector<pair<int, int>> obr(n);
vector<int> roz(m);
for (int i = 0; i < n; i++) cin >> obr[i].se >> obr[i].fi;
for (int i = 0; i < m; i++) cin >> roz[i];
sort(obr.rbegin(), obr.rend());
sort(roz.rbegin(), roz.rend());
for (pair<int, int> p : obr) if (ind < roz.size() and p.se <= roz[ind]) ind++;
cout << ind;
}
