#include <bits/stdc++.h>
using namespace std;
#define pii pair<int, int>
const int nx = 1e5+5;
int n, m, res;
vector<int> c(nx);
vector<pii> pic(nx);
bool cmp(const pii& a, const pii& b)
{
if(a.second == b.second) return a.first < b.first;
return a.second < b.second;
}
int main()
{
cin.tie(NULL)->sync_with_stdio(false);
cin >> n >> m;
for(int i=0;i<n;i++)
cin >> pic[i].first >> pic[i].second;
for(int i=0;i<m;i++)
cin >> c[i];
sort(pic.begin(), pic.begin() + n, cmp);
sort(c.begin(), c.begin() + m);
int l = 0, r = 0, prev = 0;
while(l < n)
{
auto [s, v] = pic[l];
// cout << "s : " << s << " v : " << v << '\n';
// cout << "l : " << l << " r : " << r << '\n';
while(r < m)
{
if(s <= c[r])
{
r++;
res++;
break;
}
else r++;
}
l++;
}
cout << res ;
return 0;
}
