#include <bits/stdc++.h>
#define int long long
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define sc second
#define endl "\n"
#define pii pair<int,int>
using namespace std;
const int MAXN = 1e5+5;
const int mod7 = 1e9+7;
const long long inf = 1e18;
bool CMP(pii p1, pii p2)
{
if(p1.sc == p2.sc)return p1.fi < p2.fi;
return p1.sc < p2.sc;
}
signed main()
{
ios_base::sync_with_stdio(false),cin.tie(0), cout.tie(0);
int tt=1;
//cin >> tt;
while(tt--)
{
int n,m;
cin >> n >> m;
vector<pii> slike(n);
for(int i=0; i<n; i++)cin >> slike[i].fi >> slike[i].sc;
sort(all(slike), CMP);
vector<int> ramovi(m);
for(int i=0; i<m; i++)cin >> ramovi[i];
sort(all(ramovi));
int pointer = n-1;
int rez = 0;
for(int i=m-1; i>=0; i--)
{
while(pointer >=0 && slike[pointer].fi > ramovi[i])pointer--;
if(pointer >=0)rez++;
pointer--;
}
cout << rez << endl;
}
}
