#include <bits/stdc++.h>
#include <assert.h>
#include <unordered_map>
using namespace std;

typedef long long ll;
typedef long double ld;
typedef vector < long long > vll;
typedef pair < long long, long long > pll;
typedef pair < int, int > pii;
typedef vector < int > vii;

#define csl ios_base::sync_with_stdio(false); cin.tie(NULL)
#define l(x) (((x) << 1) | 1)
#define r(x) ((l(x)) + 1)
#define mp make_pair
#define fst first
#define snd second

ll t, n, u, v, m, q, r, ql, qr, k, l, s, x, y, w, a, b;
const int N = 1e6 + 5;
const long long mod = 1e9 + 7;
const long long INF = 1LL << 57LL;
const bool JUDGE = false;
int X[60000], Y[60000];
pii S[N], W[N], _S[N], _W[N];
bool valid[N];
priority_queue < pii > wq, sq;
bool p(ll tim) {
    int x = 0;
    int i = 0;
    wq = priority_queue < pii > ();
    sq = priority_queue < pii > ();
    for (int i = 0; i < n; ++i) valid[i] = true;
    while (i < a) {
        while (x < n && W[x].fst < X[i]) {
            if (valid[W[x].snd]) {
                valid[W[x].snd] = false;
                wq.push(_S[W[x].snd]);
            }
            x++;
        }
        int j = 0;
        while (wq.size() > 0 && j < tim) {
            pii y = wq.top();
            wq.pop();
            j++;
        }
        i++;
    }
    while (wq.size() > 0) {
        pii y = wq.top();
        wq.pop();
        valid[y.snd] = true;
    }
    i = 0;
    x = 0;
    while (i < b) {
        while (x < n && S[x].fst < Y[i]) {
            if (valid[S[x].snd]) {
                sq.push(_W[S[x].snd]);
                valid[S[x].snd] = false;
            }
            x++;
        }
        int j = 0;
        while (sq.size() > 0 && (j < tim)) {
            pii y = sq.top();
            sq.pop();
            valid[y.snd] = false;
            j++;
        }
        i++;
    }
    while (sq.size() > 0) {
        pii y = sq.top();
        sq.pop();
        valid[y.snd] = true;
    }
    for (int i = 0; i < n; ++i) if (valid[i]) {
        //cout << i << "h\n";
        return false;
    }
    return true;
}
int main(){
    csl;
    if (JUDGE) {
        freopen("in.txt", "r", stdin);
        freopen("out.txt", "w", stdout);
    }
    cin >> a >> b >> n;
    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 < n; ++i) {
        cin >> W[i].fst >> S[i].fst;
        W[i].snd = S[i].snd = i;
        _S[i] = S[i];
        _W[i] = W[i];
    }
    ll lo = 1, hi = a + b + n;
    sort(W, W + n), sort(S, S + n);
    sort(X, X + a), sort(Y, Y + b);
    while (lo < hi) {
        int mid = lo + (hi - lo) / 2;
        if (p(mid)) hi = mid;
        else lo = mid + 1;
    }
    if (p(lo))  cout << lo << '\n';
    else cout << -1 << '\n';
    return 0;
}