#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> ii;
int main()
{
//freopen("i.txt","r",stdin);
ios_base::sync_with_stdio(false);
cin.tie(0);
int n, m;
cin >> n >> m;
ii stuff[n];
for(int i = 0;i < n;i++){
cin >> stuff[i].second >> stuff[i].first;
}
int arr[m];
for(int j = 0;j < m;j++){
cin >> arr[j];
}
int low = 0;
int high = m+1;
sort(stuff,stuff+n);
sort(arr,arr+m);
while(true){
int s = (low + high) / 2;
if(low == high - 1) break;
int c = m - s;
for(int i = 0;i < n;i++){
if(stuff[i].second <= arr[c]){
c++;
if(c == m) break;
}
}
if(c == m) low = s;
else high = s;
}
cout << low;
return 0;
}
