#include<bits/stdc++.h>
#define speed ios_base::sync_with_stdio(0); cin.tie(0)
#define all(x) x.begin()+1, x.end()
#define F first
#define S second
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
struct BIT {
int n;
vector<int> a;
BIT(int _n):n(_n) {
a.resize(n+1);
}
void update(int x,int v) {
while (x<=n) {
a[x]=max(a[x],v);
x+=(-x&x);
}
}
int query(int x) {
// cout<<x<<" x\n"<<flush;
int ans=0;
while (x) {
ans=max(ans,a[x]);
x-=(-x&x);
}
return ans;
}
};
int main() {
speed;
int n,m;
cin>>n>>m;
vector<pii> pt(n+1);
vector<int> fm(m+1);
for (int i=1;i<=n;i++) {
cin>>pt[i].S>>pt[i].F;
}
sort(all(pt));
for (int i=1;i<=m;i++) {
cin>>fm[i];
}
sort(all(fm));
for (int i=1;i<=n;i++) {
pt[i].S=lower_bound(all(fm),pt[i].S)-fm.begin();
pt[i].S=m-pt[i].S+1;
// cout<<pt[i].S<<" pt\n"<<flush;
}
BIT b(m);
for (int i=n;i>=1;i--) {
if (pt[i].S==0) continue;
int mx=b.query(pt[i].S-1);
int l=0,r=pt[i].S-1;
while (l<r) {
int mid=l+r>>1;
if (b.query(mid)==mx) r=mid;
else l=mid+1;
}
b.update(l+1,mx+1);
}
cout<<b.query(m)<<"\n";
return 0;
}
