#include<bits/stdc++.h>
using namespace std;
using pii = pair<int,int>;
vector<int> roomSize, roomCost;
vector<pii> offer;
int main(){
int n, m, o; cin >> n >> m >> o;
for(int i = 0;i<n;i++){
int a, b; cin >> a >> b;
roomCost.push_back(a); roomSize.push_back(b);
}
sort(roomCost.begin(),roomCost.end());
sort(roomSize.begin(),roomSize.end());
for(int i = 0;i<m;i++){
int a, b; cin >> a >> b;
offer.push_back(make_pair(a,b));
}
sort(offer.begin(),offer.end());
long long int resp = 0;
int cnt = 0;
for(int i = offer.size() - 1; i >= 0 && cnt < o; i--){
if(roomCost.empty()) break;
// printf("processing offer (%d,%d)\n",offer[i].first, offer[i].second);
auto it = lower_bound(roomSize.begin(), roomSize.end(), offer[i].second);
if(it == roomSize.end()) continue;
int roomId = it - roomSize.begin();
if(offer[i].first - roomCost[roomId] > 0){
// printf("-chose room %d (%d,%d) with %d profit\n",roomId, roomCost[roomId], roomSize[roomId], offer[i].first - roomCost[roomId]);
resp += offer[i].first - roomCost[roomId];
roomCost.erase(roomCost.begin() + roomId); roomSize.erase(roomSize.begin() + roomId);
cnt++;
}
}
cout << resp << "\n";
return 0;
}
