#include <iostream>
#include <algorithm>
#define debug(args...) //printf(args)
typedef long long llong;
const int MAX_N = 100 + 10;
const llong INF = 1000000000000000000;
int n, m, o;
std::pair<int, int> rooms[MAX_N]; // (upkeep, capacity)
std::pair<int, int> offers[MAX_N]; // (pay, demand)
bool isStored[MAX_N][MAX_N][MAX_N];
llong storedDP[MAX_N][MAX_N][MAX_N];
void setMax(llong& a, llong b) {
a = std::max(a, b);
}
void setMin(int& a, int b) {
a = std::min(a, b);
}
// dp[i][j][k] = max profit with only first i room and first j offer with at max k accepted offer
llong dp(int room, int offer, int accept) {
if (accept == 0) return 0;
if (offer == -1) return 0;
if (room == -1) return 0;
setMin(accept, offer + 1);
if (isStored[room][offer][accept]) return storedDP[room][offer][accept];
llong answer = 0;
setMax(answer, dp(room - 1, offer, accept));
setMax(answer, dp(room, offer - 1, accept));
if (rooms[room].second >= offers[offer].second) {
debug("capacity of %d > demand of %d\n", room, offer);
setMax(answer, dp(room - 1, offer - 1, accept - 1) + offers[offer].first - rooms[room].first);
}
isStored[room][offer][accept] = true;
storedDP[room][offer][accept] = answer;
debug("dp[%d][%d][%d] = %lld\n", room, offer, accept, answer);
return answer;
}
bool sortingFunction(std::pair<int, int> a, std::pair<int, int> b) {
if (a.second != b.second) return a.second < b.second;
return a.first < b.first;
}
int main() {
scanf("%d %d %d", &n, &m, &o);
for (int i = 0; i < n; i++) {
scanf("%d %d", &rooms[i].first, &rooms[i].second);
}
for (int i = 0; i < m; i++) {
scanf("%d %d", &offers[i].first, &offers[i].second);
}
std::sort(rooms, rooms + n, sortingFunction);
std::sort(offers, offers + m, sortingFunction);
llong answer = dp(n - 1, m - 1, o);
printf("%lld\n", answer);
}
