/*=========================================*
  * Auther: Riolu
  * Time: 2016.11.16
  * ©Copyright 2016 Riolu. All Rights Reserved.
  *=========================================*/

#include<cstdio>
#include<cstdlib>
#include<iostream>
#include<algorithm>
#include<vector>
#include<queue>
#include<map>
#include<set>
//#include<cmath>
#include<string>
//#include<ctime>
#include<cstring>
using namespace std;
#define v first
#define w second
typedef pair<int,int> P;
typedef long long ll;
typedef double db;
const int N =4e4+1,M=1e5+1;
int a,b,k;
int wa[N],wb[N];
//struct edge{int u,w;} e[M];
vector<P> ul[N],ur[N];

void read(){
	scanf("%d%d%d",&a,&b,&k);
	int i,x,y;
	for(i=1;i<=a;i++)scanf("%d",&wa[i]);
	for(i=1;i<=b;i++)scanf("%d",&wb[i]);
	for(i=1;i<=k;i++){
		//scanf("%d%d",&e[i].u,&e[i].v);
		scanf("%d%d",&x,&y);
		ul[x].push_back(P(y,-1));
		ur[y].push_back(P(x,-1));
	}
}



bool vis[N];
int ans;
int dfs(int side,int x,int dl,int dr){
	//ans=max(ans,val);
	int nxt,tans=0;
	//cout<<side<<' '<<x<<' '<<dl<<' '<<dr<<endl;
	
	if(side==0){
		int i,l=ul[x].size();
		for(i=0;i<l;i++){
			nxt=ul[x][i].v;
			if(nxt>dr){
				if(ul[x][i].w<0)
					ul[x][i].w=dfs(1,nxt,dl,nxt);
				tans=max(tans,ul[x][i].w);
				//cout<<x<<' '<<nxt<<' '<<ul[x][i].w<<endl;
			}
		}
		tans+=wa[x];
	}else{
		int i,l=ur[x].size();
		for(i=0;i<l;i++){
			nxt=ur[x][i].v;
			if(nxt>dl){
				if(ur[x][i].w<0)
					ur[x][i].w=dfs(0,nxt,nxt,dr);
				tans=max(tans,ur[x][i].w);
				//cout<<x<<' '<<nxt<<' '<<ur[x][i].w<<endl;
			}
		}
		tans+=wb[x];
	}
	return tans;
}

int main(){

	freopen("meibridge.in","r",stdin);
	freopen("meibridge.out","w",stdout);
	read();
	for(int i=a;i>=1;i--){
		ans=max(ans,dfs(0,i,i,0));
		//cout<<"-----------"<<endl;
		}
	printf("%d\n",ans);
	//cout<<ans<<endl;
	fclose(stdin);fclose(stdout);
	return 0;
}
/*
9
1 3 3 2 100 100 100  999 888
*/