#include <bits/stdc++.h>
#define F first
#define S second
using namespace std;
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
int n, m;
cin >> n >> m;
vector<pair<int, int>> a(n+1);
vector<int> b(m+1);
for (int i = 1; i <= n; i++) cin >> a[i].S >> a[i].F;
for (int i = 1; i <= m; i++) cin >> b[i];
sort(a.begin() + 1, a.end());
sort(b.begin() + 1, b.end());
int cur = n, cnt = 0;
for (int i = m; i >= 0; i--) {
while (cur >= 1 && a[cur].second > b[i]) cur--;
if (!cur) break;
cnt++, cur--;
}
cout << cnt;
}
