#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 1e5 + 2;
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int n, m;
cin >> n >> m;
vector<pair<int, int>> a(n);
for (int i = 0; i < n; i++) {
cin >> a[i].first >> a[i].second;
}
sort(a.rbegin(), a.rend());
vector<int> b(m);
for (int i = 0; i < m; i++) {
cin >> b[i];
}
sort(b.rbegin(), b.rend());
vector<int> bound(n);
int j = 0;
for (int i = 0; i < n; i++) {
while (j < m && a[i].first <= b[j]) j++;
bound[i] = j;
swap(a[i].first, a[i].second);
}
vector<int> ord(n);
iota(ord.begin(), ord.end(), 0);
sort(ord.begin(), ord.end(), [&] (int i, int j) {
if (a[i].first != a[j].first) return a[i].first > a[j].first;
return a[i].second > a[j].second;
});
int ans = 0;
for (int i : ord) {
if (bound[i] >= ans + 1) ans++;
}
cout << ans << en;
return 0;
}
