#include <bits/stdc++.h>
using namespace std;
int a[100005],b[100005];
int main(){
	int A,B,C,M,i,mn1=10000000,mn2=10000000,mn,x,y,z;
	cin>>A>>B>>C;
	for(i=1;i<=A;i++){
		cin>>a[i];
		if(a[i]<mn1) mn1=a[i];
	}
	for(i=1;i<=B;i++){
		cin>>b[i];
		if(b[i]<mn2) mn2=b[i];
	}
	mn=mn1+mn2;
	for(i=1;i<=C;i++){
		cin>>x>>y>>z;
		mn=min(mn,a[x]+b[y]-z);
	}
	cout<<mn;
	return 0;
}