#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define ALL(v) v.begin(),v.end()
typedef long long ll;

#include <bits/stdc++.h>
#include <atcoder/maxflow>
using namespace std;
using namespace atcoder;
template <class T> using V=vector<T>;
template <class T> using VV=V<V<T>>; //B(n,V<int>(n))

const ll INF=1e18;

int main(){
  ios::sync_with_stdio(false);
  std::cin.tie(nullptr);

  int n;
  cin>>n;
  ll sum=0;
  V<ll> B(n),C(n),MA(n);
  rep(i,n){
    cin>>B[i]>>C[i];
    MA[i]=B[i]+C[i];
    sum+=MA[i];
  }
  int m;
  cin>>m;
  V<ll> D(m),E(m);
  rep(i,m) cin>>D[i]>>E[i];
  
  mf_graph<ll> graph(2*n+2);
  int s=2*n,t=2*n+1;
  rep(i,n) graph.add_edge(s,i,MA[i]-C[i]);
  rep(i,n) graph.add_edge(i,i+n,MA[i]);
  rep(i,n) graph.add_edge(i+n,t,MA[i]-B[i]);
  rep(i,m) graph.add_edge(D[i],E[i]+n,INF);
  cout<<sum-graph.flow(s,t)<<endl;
  
  return 0;
}