#include <bits/stdc++.h>
//N8H+R!dg!ZZ5=+6
using namespace std;
using ll = int;
const ll N=1e5+29;
#define f first
#define s second
ll n,m,c[N];
ll b[N];
ll ans;
pair<ll,ll>a[N];
ll check(ll k){
ll j=m-k+1;
for(ll i=1;i<=n;i++){
if(c[i]<=b[j]){
j++;
if(j>m)return 1;
}
}
return 0;
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cin>>n>>m;
for(ll i=1;i<=n;i++){
cin>>a[i].s>>a[i].f;
}sort(a+1,a+1+n);
for(ll i=1;i<=m;i++){
cin>>b[i];
}sort(b+1,b+1+m);
for(ll i=1;i<=n;i++)c[i]=a[i].s;
ll l=0,r=min(n,m);
while(l<r){
ll mid=(r+l+1)>>1;
if(check(mid))l=mid;
else r=mid-1;
}
cout<<l;
}
