#include <bits/stdc++.h>
using namespace std;
int n,m;
pair<int,int>a[100005];
int v[100005];
bool cmp(pair<int,int> A, pair<int,int> B)
{
if (A.first != B.first)
return A.first > B.first;
return A.second > B.second;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
cin >> n >> m;
for (int i = 1; i <= n; i++)
cin >> a[i].second >> a[i].first;
for (int i = 1; i <= m; i++)
cin >> v[i];
sort(v + 1,v + m + 1);
reverse(v + 1,v + m + 1);
sort(a + 1,a + n + 1,cmp);
int ans = 0;
int ind = 1;
for (int i = 1; i <= m; i++)
{
while (ind <= n and a[ind].second > v[i])
ind++;
if (ind == n + 1)
break;
ind++;
ans++;
}
cout << ans;
return 0;
}
