#include <bits/stdc++.h>
#define ll long long
#define ff first
#define ss second
#define pb push_back
#define all(x) x.begin(), x.end()
#define vodka void
#define ertunt return
using namespace std;
int main() {
ios::sync_with_stdio(0); cin.tie(0);
ll n,m;
cin >> n >> m;
pair<ll,ll>a[n];
for(ll i = 0; i < n; i++)cin >> a[i].ss >> a[i].ff;
ll c[m];
for(ll i = 0; i < m; i++)cin >> c[i];
sort(a,a+n);
sort(c,c+m);
ll ans = 0, cur = m-1;
for(ll i = n-1; i >= 0; i--){
if(cur>=0 && c[cur]>=a[i].ss){
ans++;
cur--;
}
}
cout << ans;
}
