#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
typedef pair<ll,ll> pairz;
const int N = 1e3+5;
ll tc = 1;
vector<pairz> vec;
vector<ll> bing;
bool visited[N];
ll n, m, s, v, a;
bool cmp(pairz a, pairz b){
return a.second < b.second;
}
void pameran(){
// a.second -> harga
// a.first -> size
sort(vec.begin(), vec.end(), cmp);
ll curweight = 0, curprice = 0, ans = 0;;
for(int i=0;i<m;i++){
for(int j=0;j<n;j++){
if(vec[j].first > bing[i]) continue;
if((curprice < vec[j].second && visited[j] == false) && curweight < vec[j].first){
curprice = vec[j].second;
curweight = vec[j].first;
ans++;
visited[j] = true;
break;
}
else continue;
}
}
cout << ans << endl;
}
void input(){
cin >> n >> m;
for(int i=0;i<n;i++){
cin >> s >> v;
vec.pb(make_pair(s,v));
visited[vec.size()-1] = false;
}
for(int i=0;i<m;i++){
cin >> a;
bing.pb(a);
}
pameran();
}
int main()
{
// cin >> tc;
while(tc--) input();
}
