#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vii;
typedef pair<int,int> pi;
typedef vector<pi> pii;
#define REP(i,a,b) for(int i=a;i<b;i++)
#define F first
#define S second
#define PB push_back
#define MP make_pair
ll INF=1e18+10;
ll M=1e9+7;
int main() {
//ios::sync_with_stdio(0);
//cin.tie(0);
//freopen("test_input.txt", "r", stdin);
//freopen("test_output.txt", "w", stdout);
int n,m;cin>>n>>m;
pii a(n);
REP(i,0,n)cin>>a[i].S>>a[i].F;
sort(a.begin(),a.end());
vi c(m);
REP(i,0,m)cin>>c[i];
sort(c.begin(),c.end());
int ans=0;n--;
while(m--){
while(n>=0&&a[n].S>c[m])n--;
if(n>=0){
ans++;
n--;
}
}
cout<<ans;
}
