#include <bits/stdc++.h>
using namespace std;
const int MAXN = 100000 + 5;
int n, m, s[MAXN], v[MAXN], c[MAXN];
pair<int,int> a[MAXN];
bool can(int k)
{
if (k == 0) return true;
int mk = m - k;
int p = 0;
for (int i = 0; i < n && p < k; ++i)
{
if (a[i].first <= c[mk + p]) p++;
}
return p == k;
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> m;
for (int i = 0; i < n; ++i)
{
cin >> s[i] >> v[i];
a[i] = {s[i], v[i]};
}
for (int j = 0; j < m; ++j) cin >> c[j];
sort(a, a + n, [](const pair<int,int>& p1, const pair<int,int>& p2)
{
if (p1.second != p2.second) return p1.second < p2.second;
return p1.first < p2.first;
});
sort(c, c + m);
int l = 0, h = min(n, m);
while (l < h)
{
int mid = (l + h + 1) / 2;
if (can(mid)) l = mid;
else h = mid - 1;
}
cout << l;
}
