#include <bits/stdc++.h>
using namespace std;
#define name "exhibition"
#define MAXN 100005
#define pb push_back
#define pf push_front
#define ll long long
#define ii pair<int, int>
#define fs first
#define sc second
#define ill pair<int, ll>
#define lli pair<ll, int>
#define llll pair<ll, ll>
#define all(v) v.begin(),v.end()
#define uni(v) v.erase(unique(all(v)),v.end())
#define bit(n,i) (((n)>>(i))&1)
#define FOR(i,a,b) for (int i=(a),_b=(b); i<=_b; i++)
#define FORD(i,a,b) for (int i=(a),_b=(b); i>=_b; i--)
#define MASK(i) (1LL<<(i))
const int INF=1e9;
const int MOD=1e9+7;
void add(int &u, int v){
u+=v;
if (u>=MOD) u-=MOD;
}
void sub(int &u, int v){
u-=v;
if (u<0) u+=MOD;
}
void minimize(int &u, int v){
u=min(u,v);
}
void maximize(int &u, int v){
u=max(u,v);
}
long long Rand(long long l, long long r){
ll tmp=0;
FOR(i,1,4) tmp=((tmp<<15)^(((1<<15)-1)&rand()));
return l+tmp%(r-l+1);
}
int n,m;
ii a[MAXN];
int b[MAXN];
int l[MAXN];
ii dp[MAXN];
int main()
{
ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
cin>>n>>m;
FOR(i,1,n) cin>>a[i].sc>>a[i].fs;
FOR(i,1,m) cin>>b[i];
sort(a+1,a+n+1);
sort(b+1,b+m+1);
FOR(i,1,n){
l[i]=lower_bound(b+1,b+m+1,a[i].sc)-b;
}
int j=m;
int ans=0;
FORD(i,n,1){
if (j>=1&&b[j]>=a[i].sc){
++ans;
--j;
}
}
cout<<ans;
return 0;
}
