#include<iostream>
#include<cstdio>
#include<queue>
#include<cstring>
using namespace std;
const int maxn=50000;
const int maxm=100000;
typedef long long LL;
struct zty
{
	bool ina; LL value; int x;
};
struct edges
{
	int f; int t; int next; int rnext;
} e[maxm];
int heada[maxn];
int headb[maxn];
int tot=0;
void ade(int f,int t)
{	
	tot++;
	e[tot].f=f;
	e[tot].t=t;
	e[tot].next=heada[f];
	e[tot].rnext=headb[t];
	heada[f]=headb[t]=tot;
}
int va[maxn];
int vb[maxn];
bool visa[maxn];
bool visb[maxn];
int a,b,k;
queue<zty> q;
LL ma1=0;
LL ma2=0;
LL ans;
void bfs()
{
	memset(visa,0,sizeof(visa));
	memset(visb,0,sizeof(visb));
	zty rig; rig.x=1; rig.ina=1; rig.value=va[1];
	q.push(rig);
	while(!q.empty())
	{
		zty x=q.front(); q.pop(); 
		if(x.value>ma1)
		{
			ma2=ma1;
			ma1=x.value;
		}
		else
		{
			ma2=max(ma2,x.value);
		}
		if(x.ina)
		{	
			visa[x.x]=1;
			for(int i=heada[x.x];~i;i=e[i].next)
			{
				if(!visb[e[i].t])
				{
					zty nx;
					nx.x=e[i].t;
					nx.ina=0;
					nx.value=x.value+vb[e[i].t];
					q.push(nx);
				}
			}
		}
		else
		{
			visb[x.x]=1;
			for(int i=headb[x.x];~i;i=e[i].rnext)
			{
					if(!visa[e[i].f])
					{
						zty nx;
						nx.x=e[i].f;
						nx.ina=1;
						nx.value=x.value+va[e[i].f];
						q.push(nx);
					}
			}
		}
	}
}
int main()
{	
	freopen("meibridge.in","r",stdin);
	freopen("meibridge.out","w",stdout);
	memset(heada,-1,sizeof(heada));
	memset(headb,-1,sizeof(headb));
	scanf("%d%d%d",&a,&b,&k);
	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=1;i<=k;i++) 
	{
		int f,t;
		scanf("%d%d",&f,&t);
		ade(f,t);
	}
	bfs();
	ans=ma1+ma2;
	cout<<ans<<endl;
	return 0;
}