#pragma GCC optimize("O3")
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define pb push_back
#define ff first
#define ss second
#define MOD 1000000009
#define INF 1000000019
#define INFL 1000000000000000099LL
ll n,q,s,t,a,b,c,d,ans,bst,k,e,m,pier,h,w,u;
vector<ll>v;
vector<pair<ll,ll>>v2;
int main()
{
ios_base::sync_with_stdio(0);cin.tie(0);
cin>>n>>m;
for(ll i=0;i<n;i++){
cin>>a>>b;
v2.pb({b,a});
}
for(ll i=0;i<m;i++){
cin>>a;
v.pb(a);
}
sort(v.begin(),v.end());
sort(v2.begin(),v2.end());
while(v.size() && v2.size()){
if(v2.back().ss>v.back())v2.pop_back();
else{
ans++;
v.pop_back();
v2.pop_back();
}
}
cout<<ans;
}
