#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;
#define endl '\n'
#define ll long long
#define pi pair<int, int>
#define f first
#define s second
const int maxn = 100000;
int n, m;
pi a[maxn];
int b[maxn];
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m;
for(int i = 0; i < n; i++) cin >> a[i].s >> a[i].f;
for(int i = 0; i < m; i++) cin >> b[i];
sort(a, a + n, greater<pi>());
sort(b, b + m, greater<int>());
int ret = 0;
for(int i = 0; i < n; i++){
if(ret < m && a[i].s <= b[ret]) ret++;
}
cout << ret << endl;
return 0;
}
