#include <iostream>
#include <iomanip>
#include <vector>
#include <cmath>
#include <algorithm>
#include <set>
#include <queue>
#include <map>
#include <stack>
#include <bitset>
#include <string>
#include <cstring>
#include <iterator>
#include <random>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef long double ld;
const ll dim = 5*1e6+7;
//const ll mod = 1e9 + 7;
const ll inf = 1e18 + 77;
#define endl "\n"
#define fi first
#define pb push_back
#define se second
#define vll vector<ll>
ll n, m;
pll a[dim];
ll b[dim];
ll check(ll len){
ll p1=m-len+1;
ll cnt=0;
for(int i=1; i<=n; i++){
if(b[p1]>=a[i].se){
p1++;
cnt++;
}
}
if(cnt>=len)return 1;
return 0;
}
int main() {
ll k, s, t, u0, v0;
cin>>n>>m;
for(int i=1; i<=n; i++) {
cin>>a[i].se>>a[i].fi;
}
sort(a+1, a+1+n);
for(int i=1; i<=m; i++){
cin>>b[i];
}
sort(b+1, b+1+m);
ll l=0;
ll r=min(n, m);
while(r-l>=1){
ll mid=(l+r+1)/2;
if(check(mid)){
l=mid;
}
else{
r=mid-1;
}
}
cout<<l<<endl;
return 0;
}
