#include <bits/stdc++.h>
#define f first
#define s second
using namespace std;
#define int long long
const int maxn = 1e5 + 69;
int n, m, c[maxn];
pair<int, int> a[maxn];
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int tt = 1;
//cin >> tt;
while(tt--) {
cin >> n >> m;
for(int i = 0;i < n;i++)
cin >> a[i].s >> a[i].f;
for(int i = 0;i < m;i++)
cin >> c[i];
sort(c, c + m);
sort(a, a + n);
int i = n - 1, j = m - 1, ans = 0;
while(i >= 0 && j >= 0) {
if(c[j] >= a[i].s)
++ans, --j;
--i;
}
cout << ans;
}
return 0;
}
