#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>
using namespace std;
vector <pair <int, int>> pictures (100005);
vector <int> frames (100005);
int n, m;
bool compare (pair <int, int> a, pair <int, int> b)
{
if (a.second!=b.second)
{
return a.second>b.second;
}
return a.first>b.first;
}
int main()
{
cin >> n >> m;
for (int i=1;i<=n;i++)
{
cin >> pictures[i-1].first >> pictures[i-1].second;
}
for (int i=1;i<=m;i++)
{
cin >> frames[i-1];
}
sort (pictures.begin(), pictures.begin()+n, compare);
sort (frames.begin(), frames.begin()+m, greater<int>());
int i=0, j=0, ret=0;
while (i<n && j<m)
{
if (pictures[i].first<=frames[j])
{
i++;
j++;
ret++;
}
else
{
i++;
}
}
cout << ret;
return 0;
}
