//KZNS
#include <cstdio>
#include <utility>
#include <algorithm>
using namespace std;
#define Smax 40003
#define Mmax 100003
typedef pair<int, int> pr;
int A, B, M;
int VA[Smax];
int VB[Smax];
pr Rls[Mmax];
void init() {
    scanf("%d %d %d", &A, &B, &M);
    for (int i = 1; i <= A; i++)
        scanf("%d", VA+i);
    for (int i = 1; i <= B; i++)
        scanf("%d", VB+i);
    for (int i = 0; i < M; i++)
        scanf("%d %d", &Rls[i].first, &Rls[i].second);
}
int FA[Smax];
int FB[Smax];
int ans = 0;
void work() {
    sort(Rls, Rls+M);
    for (int i = 1; i <= A; i++)
        FA[i] = VA[i];
    for (int i = 1; i <= B; i++)
        FB[i] = VB[i];
    int a, b, fa, fb;
    for (int i = 0; i < M; i++) {
        a = Rls[i].first;
        b = Rls[i].second;
        fa = FA[a];
        fb = FB[b];
        FA[a] = max(FA[a], fb + VA[a]);
        FB[b] = max(FB[b], fa + VB[b]); 
    }
    for (int i = 1; i <= A; i++)
        ans = max(ans, FA[i]);
    for (int i = 1; i <= B; i++)
        ans = max(ans, FB[i]);
    printf("%d\n", ans);
}
int main() {
    freopen("meibridge.in", "r", stdin);
    freopen("meibridge.out", "w", stdout);
    init();
    work();
    return 0;
}
//UBWH