//雪花飄飄北風嘯嘯
//天地一片蒼茫
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define ll long long
#define ii pair<ll,ll>
#define iii pair<ii,ll>
#define fi first
#define se second
#define endl '\n'
#define debug(x) cout << #x << " is " << x << endl;
#define rep(x,start,end) for(auto x=(start)-((start)>(end));x!=(end)-((start)>(end));((start)<(end)?x++:x--))
#define all(x) (x).begin(),(x).end()
#define sz(x) (int)(x).size()
ll MAX(ll a){return a;}
ll MIN(ll a){return a;}
template<typename... Args>
ll MAX(ll a,Args... args){return max(a,MAX(args...));}
template<typename... Args>
ll MIN(ll a,Args... args){return min(a,MIN(args...));}
#define indexed_set tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>
mt19937 rng(chrono::system_clock::now().time_since_epoch().count());
int n,m;
vector<ii> v;
vector<int> frame;
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin>>n>>m;
int a,b;
rep(x,0,n){
cin>>a>>b;
v.push_back(ii(a,b));
}
rep(x,0,m){
cin>>a;
frame.push_back(a);
}
sort(all(v),[](ii i,ii j){
if (i.se!=j.se) return i.se<j.se;
else return i.fi<j.fi;
});
sort(all(frame),[](int i,int j){
return i>j;
});
int ans=0;
for (auto &it:frame){
while (!v.empty() && v.back().fi>it) v.pop_back();
if (v.empty()) break;
v.pop_back();
ans++;
}
cout<<ans<<endl;
}
