#include<bits/stdc++.h>
#define fi first
#define se second
using namespace std;
using ll = long long;
const int N = 1e5;
int n,m;
pair<int,int>a[N+5];
int b[N+5];
bool cmp(pair<int,int> x,pair<int,int> y){
if(x.se!=y.se) return x.se < y.se;
return x.fi < y.fi;
}
int main(){
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin >> n >> m;
for(int i = 1 ; i <= n ; ++i)
cin >> a[i].fi >> a[i].se;
for(int i = 1 ; i <= m ; ++i)
cin >> b[i];
sort(a+1,a+1+n,cmp);
sort(b+1,b+1+m);
int j = n;
int ans = 0;
// for(int i = 1 ; i <= n ; ++i) cout << a[i].fi << ' ' << a[i].se << '\n';
for(int i = m ; i >= 1 ; --i){
while(a[j].fi>b[i]) j--;
if(j > 0 && a[j].fi <= b[i]){
ans++;
j--;
}
}
cout << ans;
return 0;
}
