#include <bits/stdc++.h>
using namespace std;
#define ll long long
int main(){
ll n,m,o;
cin>>n>>m>>o;
vector<pair<ll,ll>> V;
for(int i=0;i<n;i++){
ll a,b;
cin>>a>>b;
V.push_back({a,b});
}
sort(V.begin(),V.end());
priority_queue<pair<ll,ll>> pq;
vector<ll> ganancias;
vector<pair<ll,ll>> pedidos;
ll ind=0;
for(int i=0;i<m;i++){
ll a,b;
cin>>a>>b;
pedidos.push_back({b,a});
}
sort(pedidos.begin(),pedidos.end());
for(int i=0;i<n;i++){
ll newind=ind-1;
for(int j=ind;j<m;j++){
if(pedidos[j].first<=V[i].second){
pq.push({pedidos[j].second,pedidos[j].first});
}else{
break;
}
newind=j;
}
ind=newind+1;
ll xd=0;
if(!pq.empty()){
xd=pq.top().first;
}
if(xd>V[i].first){
pq.pop();
ganancias.push_back(xd-V[i].first);
}
}
sort(ganancias.rbegin(),ganancias.rend());
ll ans=0;
for(int i=0;i<o;i++){
ans+=ganancias[i];
}
cout<<ans;
}
