#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 1e5+5;
int n, m;
ll frm[N];
vector<pair<ll,ll>> pic;
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n >> m;
for( int i=0;i<n;i++ )
{
ll a, b;
cin >> a >> b;
pic.push_back( {-b, -a} );
}
for( int i=0;i<m;i++ )
{
ll a;
cin >> a;
frm[i] = -a;
}
sort( pic.begin(), pic.end() );
sort( frm, frm+m );
int ans = 0;
for( int i=0;i<n;i++ )
{
if( ans >= m ) break;
if( frm[ans] <= pic[i].second ) ans++;
}
cout << ans << "\n";
return 0;
}
