#pragma GCC optimize("O3")
#include "bits/stdc++.h"
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
tree<int,int,greater<int>,rb_tree_tag,tree_order_statistics_node_update> map_t;
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define F0R(i, a) for(int i = 0; i < (a); ++i)
#define sz(x) (int)x.size()
#define SORT(x) sort(x.begin(),x.end())
#define ERASE(x) x.erase(unique(x.begin(),x.end()),x.end())
#define POSL(x,v) (lower_bound(x.begin(),x.end(),v)-x.begin())
#define POSU(x,v) (upper_bound(x.begin(),x.end(),v)-x.begin())
#define REV(x) reverse(x.begin(),x.end())
int dx[]={-1,0,1,0};
int dy[]={0,-1,0,1};
int n,m;
const int mxN=1e5+5;
pair<int,int> arr[mxN];
int sizes[mxN];
bool comp(pair<int,int> a,pair<int,int> b) {
if(a.second==b.second)
return a.first<b.first;
return a.second<b.second;
}
int main() {
// freopen("input.txt", "r", stdin);
// freopen("output.txt", "w", stdout);
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> m;
F0R(i,n)
cin >> arr[i].first >> arr[i].second;
F0R(i,m)
cin >> sizes[i];
sort(arr,arr+n,comp);
sort(sizes,sizes+m);
int cur=n-1;
int res=0;
for(int i=m-1; ~i; i--) {
while(~cur && arr[cur].first>sizes[i])
cur--;
if(~cur) {
res++; cur--;
}
}
cout << res;
return 0;
}
