#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
bool owo(pair<int,int> a,pair<int,int> b){
return a.se>b.se;
}
int main(){
// ifstream fin("input.txt");
// ofstream fout("output.txt");
// fin>>c;
// fout<<c;
int c,p; cin>>c>>p;
vector<pair<int,int>> ms(c);
vector<int> q(p);//problem quality
vector<int> d(p);//-satisfaction
vector<bool> visited(p,0);
int ans=0;
for(int i=0;i<c;i++){
cin>>ms[i].fi>>ms[i].se;
}
for(int i=0;i<p;i++){
cin>>q[i]>>d[i];
}
sort(ms.begin(),ms.end(),owo);
for(int i=0;i<c;i++){
for(int j=0;j<p;j++){
if(q[j]<ms[i].fi) continue;
if(d[j]>ms[i].se) continue;
if(!visited[j]) {
ans+=ms[i].se-d[j];
visited[j]=1;
}
}
}
cout<<ans;
}
