//violent code by dudu
#include<iostream>
#include<cstring>
#include<cstdio>
#include<algorithm>
#include<queue>
using namespace std;

const int KN =1e5+10;
const int KM =6e5+10;

int A,B,N,M,G_cnt;
int data[KN];
int first[KN];
struct Graph{
	int fr,to,cost,next;
	Graph(){fr=to=cost=next=0;};
	Graph(int fr_,int to_,int cost_,int next_){
		fr=fr_,to=to_,cost=cost_,next=next_;
	}
	Graph operator =(const Graph tmp){
		fr=tmp.fr,to=tmp.to,cost=tmp.cost,next=tmp.next;
		return *this;
	}
}G[KM];
int d[KN];

void init(){
	scanf("%d %d %d",&A,&B,&M);
	N=A+B;
	for(int i=1;i<=N;i++) scanf("%d",&data[i]);
	int fr,to;
	for(int i=1;i<=M;i++){
		scanf("%d %d",&fr,&to);
		G[++G_cnt]=Graph(fr,A+to,data[A+to],first[fr]);first[fr]=G_cnt;
		G[++G_cnt]=Graph(A+to,fr,data[fr],first[A+to]);first[A+to]=G_cnt;
	}
	for(int i=1;i<=N;i++){
		G[++G_cnt]=Graph(0,i,data[i],first[0]);first[0]=G_cnt;
		G[++G_cnt]=Graph(i,N+1,0,first[i]);first[i]=G_cnt;
	}
}
struct Status{
	int v,now,last;
	Status(){v=now=last=0;}
	Status(int v_,int now_,int last_){
		v=v_,now=now_,last=last_;
	}
};
struct my_cmp{
	bool operator ()(const Status a,const Status b){
		return a.v<b.v;
	}
};
void dij(){
	memset(d,0,sizeof d);
	priority_queue<Status,vector<Status>,my_cmp> q;
	q.push(Status(0,0,0));
	while(!q.empty()){
		int nowv=q.top().v,now=q.top().now,last=q.top().last;
		q.pop();
		for(int i=first[now];i;i=G[i].next){
			int to=G[i].to,cost=G[i].cost;
			if(to<=last) continue;
			d[to]=max(d[to],nowv+cost);
			q.push(Status(nowv+cost,to,now));
		} 
	}
	printf("%d",d[N+1]);
}

int main(){
//	freopen("test.in","r",stdin);
	freopen("meibridge.in","r",stdin);
	freopen("meibridge.out","w",stdout);
	init();
	dij();	
	return 0;
}