#include<bits/stdc++.h>
using namespace std;
bool M1;
#define PI 3.14159265358979323846
#define sz(a) (int)a.size()
#define all(x) x.begin(),x.end()
#define ii pair<int,int>
#define iii pair<int,ii>
#define iv pair<ii,ii>
#define se second
#define fi first
#define ffi fi.fi
#define sfi se.fi
#define sse se.se
#define fse fi.se
#define lt(i, c, d) for(int i = c; i <= d; ++i)
#define fl(i, c, d) for(int i = d; i >= c; --i)
#define pb push_back
#define emb emplace_back
#define emf emplace_front
#define em emplace
#define look_memory cerr<<abs(&M2-&M1)/1024.0/1024<<'\n'
#define look_time   cerr << "TIME : " << clock() * 0.001 << "s" <<'\n'
const int N=1e6+5,lg=30,mod=1e9+7;
mt19937 rd(chrono::steady_clock::now().time_since_epoch().count());
int Rand(int u,int v){
 return u+rd()%(v-u+1);
}
int dx[]={1,0,-1,0,1,1,-1,-1};
int dy[]={0,-1,0,1,1,-1,1,-1};
int node,frame;
ii a[N];
int c[N],G[N];
multiset<int>s;
bool M2;
void solve(){
	cin >> node >> frame;
	for(int i=1;i<=node;++i)cin >> a[i].fi >> a[i].se,G[i]=2e9;
	for(int i=1;i<=frame;++i)cin >> c[i];
	sort(c+1,c+1+frame);
	sort(a+1,a+1+node);
	G[0]=0;
	int ans=0;
	for(int j=1,i=1;i<=frame;++i){
		while(j<=node&&a[j].fi<=c[i]){
			s.insert(a[j].se);
			++j;
		}
		for(int k=node;k>=1;--k){
			auto it=s.lower_bound(G[k-1]);
			// cout <<i<<" "<<k<<" "<<G[k-1]<<'\n';
			if(it==s.end())continue;
			if(*it<G[k]){
				if(G[k]!=2e9){
					s.insert(G[k]);
				}
					G[k]=*it;
					s.erase(it);
					ans=max(ans,k);
			}
		}
	}
	cout << ans;
}
main()
{
  srand(time(0));
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    #define task "aws"
    if(fopen(task".inp","r")){
      freopen(task".inp","r",stdin);
      freopen(task".out","w",stdout);
    }
    int t=1;
 //   cin >> t;
while(t--){
    solve();cout<<'\n';
}
look_memory;
look_time;
}
컴파일 시 표준 에러 (stderr) 메시지
joi2019_ho_t2.cpp:67:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   67 | main()
      | ^~~~
joi2019_ho_t2.cpp: In function 'int main()':
joi2019_ho_t2.cpp:75:14: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   75 |       freopen(task".inp","r",stdin);
      |       ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
joi2019_ho_t2.cpp:76:14: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   76 |       freopen(task".out","w",stdout);
      |       ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~| # | Verdict  | Execution time | Memory | Grader output | 
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