#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define pii pair<int,int>
#define sz size()
#define all(v) v.begin(),v.end()
#define fi first
#define se second
const int N = 5e5;
const int mod = 1e9+7;
const ll INF = 1e18;
const int di[] = {1, -1, 0, 0};
const int dj[] = {0, 0, 1, -1};
void solve() {
int n,m;
cin>>n>>m;
pii a[n+1];
int b[m+1];
for(int i = 1; i <= n; i++){
cin>>a[i].se>>a[i].fi;
}
for(int i = 1; i <= m; i++){
cin>>b[i];
}
sort(a+1,a+n+1);
sort(b+1,b+m+1);
int ans=0;
for(int i = n, j = m; i >= 1 && j >= 1; i--){
if(b[j]>=a[i].se){
ans++;
j--;
}
}
cout<<ans<<"\n";
}
int main() {
//freopen("cowrun.in","r",stdin);
//freopen("cowrun.out","w",stdout);
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
int t=1;
//cin>>t;
while(t--) {
solve();
}
return 0;
}
