#include<bits/stdc++.h>
using namespace std;
#define int long long
#define in pair<int, int>
#define f first
#define s second
#define pb push_back
#define pob pop_back
#define INF (int)1e17
#define MX (int)3e5+5
#define fast() ios_base::sync_with_stdio(false); cin.tie(NULL)
signed main()
{
fast();
int n, m;
cin >> n >> m;
vector<in> vs(n+1);
vector<int> c(m+1);
for(int i = 1; i <= n; i++)
cin >> vs[i].s >> vs[i].f;
for(int i = 1; i <= m; i++)
cin >> c[i];
vs[0] = {INF, INF};
c[0] = INF;
sort(vs.rbegin(), vs.rend());
sort(c.rbegin(), c.rend());
int cnt = 0;
int l = 1;
for(int r = 1; r <= m; r++)
{
while((l <= n) && (vs[l].s > c[r]))
l++;
if(l == (n+1))
break;
cnt++;
l++;
}
cout << cnt << "\n";
return 0;
}
