#include <bits/stdc++.h>
#define ll long long
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pb push_back
#define ff first
#define ss second
using namespace std;
const int N=2*1e5;
int n,m,k,i,j,ans;
vector<int> a;
vector<pii> p;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL); cout.tie(NULL);
cin>>n>>m;
for(k=0; k<n; k++){
int x,y;
cin>>x>>y;
p.pb({y,x});
}
for(k=0; k<m; k++){
int x;
cin>>x;
a.pb(x);
}
sort(p.rbegin(),p.rend());
sort(a.rbegin(),a.rend());
ans=0;
for(k=0; k<n; k++){
if(p[k].ss<=a[k])ans++;
}
cout<<ans;
}
