#ifndef LOCAL
#include"robots.h"
#endif // LOCAL
#include <bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define ar array
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
const int maxn = 1e5 + 5;
int putaway(int A, int B, int T, int X[], int Y[], int W[], int S[])
{
sort(X, X + A); sort(Y, Y + B);
vector<ii> ve;
for(int i = 0; i < T; ++i)
ve.eb(W[i], S[i]);
sort(ve.begin(), ve.end());
auto check = [&](int mx)
{
priority_queue<int> pq;
int cur = 0;
for(int i = 0; i < A; ++i){
while(cur < T && ve[cur].fi < X[i]){
pq.push(ve[cur++].se);
}
for(int j = 0; j < mx; ++j){
if(pq.empty()) break;
pq.pop();
}
}
for(int i = cur; i < T; ++i)
pq.push(ve[i].se);
for(int i = B - 1; i >= 0; --i){
for(int j = 0; j < mx; ++j){
if(pq.empty()) break;
if(pq.top() >= Y[i]) return false;
pq.pop();
}
}
return pq.empty();
};
if(!check(T)) return -1;
int l = 1, r = T, mid;
while(l <= r){
mid = (l + r) / 2;
if(!check(mid)) l = mid + 1;
else r = mid - 1;
}
return l;
}
#ifdef LOCAL
signed main(void)
{
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#ifdef LOCAL
freopen("A.INP", "r", stdin);
freopen("A.OUT", "w", stdout);
#endif // LOCAL
int A, B, T;
cin >> A >> B >> T;
int X[A], Y[B], W[T], S[T];
for(int i = 0; i < A; ++i)
cin >> X[i];
for(int i = 0; i < B; ++i)
cin >> Y[i];
for(int i = 0; i < T; ++i)
cin >> W[i] >> S[i];
cout << putaway(A, B, T, X, Y, W, S);
}
#endif
