#include<iostream>

 #include<cstdio>

 #include<queue>

 #include<algorithm>

 using namespace std;

 const int MAXN=+;

 struct rec

 {

     int a,b;

     bool operator < (const rec& x) const

     {

         return a<x.a;

     }

 };

 rec cow[MAXN],sunscreen[MAXN];

 int C,L,ans=;

 int main()

 {

     scanf("%d%d",&C,&L);

     for (int i=;i<C;i++) scanf("%d%d",&cow[i].a,&cow[i].b); //a:min b:max

     for (int i=;i<L;i++) scanf("%d%d",&sunscreen[i].a,&sunscreen[i].b);//a:effect b:num

     priority_queue< int,vector<int>,greater<int> > pque;

     sort(cow,cow+C);

     sort(sunscreen,sunscreen+L);

     int j=;

     for (int i=;i<L;i++)

     {

         while (j<C && cow[j].a<=sunscreen[i].a)

         {

             pque.push(cow[j].b);

             j++;

         }

         while (!pque.empty() && sunscreen[i].b)//莫忘队列为空时也不执行

         {

             int temp=pque.top();

             pque.pop();

             if (temp<sunscreen[i].a) continue;

             sunscreen[i].b--;

             ans++;

         }

     }

     cout<<ans<<endl;

     return ;

 }