#include <bits/stdc++.h>
using namespace std;
#define forn(i,n) for(int i=0;i<int(n);i++)
#define forsn(i,s,n) for(int i=int(s);i<int(n);i++)
#define dforn(i,n) for(int i=int(n)-1;i>=0;i--)
#define dforsn(i,s,n) for(int i=int(n)-1;i>=int(s);i--)
#define fst first
#define snd second
#define pb push_back
#define eb emplace_back
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
typedef long long ll;
typedef vector<ll> vll;
typedef vector<int> vi;
typedef pair<int,int> ii;
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
int n,m;
cin>>n>>m;
vector<ii> p(n);
forn(i,n) cin>>p[i].snd>>p[i].fst;
vi f(m);
forn(i,m) cin>>f[i];
sort(all(p));
sort(all(f));
int j=m-1,ans=0;
dforn(i,n){
if(j>=0&&p[i].snd<=f[j]) ans++,j--;
}
cout<<ans<<'\n';
return 0;
}
