// UUID: 96b06675-2ab4-49e4-86d2-73f704b12265
#include <bits/stdc++.h>
using namespace std;
using ll=long long;
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define vi vector<int>
#define pii pair<int,int>
void solve(){
int n, m;
cin>>n>>m;
vector<pair<int,int>> kep(n);
vector<int> c(m);
for (int i=0;i<n;i++) cin>>kep[i].second>>kep[i].first;
for (int i=0;i<m;i++) cin>>c[i];
sort(c.rbegin(), c.rend());
sort(kep.begin(), kep.end());
int ans=0;
int cur=0;
while (cur<m && !kep.empty()){
auto v = kep.back();
kep.pop_back();
if (v.second<=c[cur]) {ans++;cur++;}
}
cout<<ans;
}
int main() {
ios_base::sync_with_stdio(0);cin.tie(0);
int t=1;
//cin>>t;
while (t--){
solve();
}
}
