#include <bits/stdc++.h>
#define int long long
#define vi vector<int>
#define vvi vector<vi>
#define ii pair<int, int>
#define f first
#define s second
#define str string
#define pb push_back
#define fun function
#define P 31
#define mod 1'000'000'007
#define inf 1'000'000'000'000'000'000
#define all(x) (x).begin(), (x).end()
#define oopt cout.tie(0);ios_base::sync_with_stdio(false);
using namespace std;
void solve()
{
int n, m, o;
cin >> n >> m >> o;
multiset<ii> sb;
for (int i = 0; i < n; i++)
{
int cn, kp;
cin >> cn >> kp;
sb.insert({kp, cn});
}
vector<ii> pn(m);
for (ii&v:pn)
cin >> v.f >> v.s;
sort(all(pn));
reverse(all(pn));
vi rz;
for (int i = 0; i < m; i++)
{
if (sb.empty()) break;
auto it = sb.lower_bound({pn[i].s, 0});
if (it == sb.end()) continue;
if (it->f < pn[i].s) it++;
rz.pb(pn[i].f-it->s);
sb.erase(it);
}
sort(all(rz));
reverse(all(rz));
int rez = 0;
for (int i = 0; i < min((int)rz.size(), o); i++)
rez += max(rz[i], 0ll);
cout << rez << "\n";
}
signed main()
{
oopt;
solve();
return 0;
}
