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// Piotr Golda
#define _CRT_SECURE_NO_WARNINGS  
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <vector>
#include <cstdlib>
using namespace std;
#define LLD long long int
#define MAX_NUM 200000
#define MAX_REACTIONS_NUM 500000

class Node;
class Reaction;

int M,N,K;
int Vol[MAX_NUM];
Node* Vial[MAX_NUM];
Reaction* Reactions;

class Reaction
{
public:
	int m_a;
	int m_b;
	int m_time;

	Reaction(){}

	Reaction(int p_a, int p_b, int p_time)
		:m_a(p_a), m_b(p_b), m_time(p_time){}


	bool operator<(const Reaction& p_rhs) const
	{
		return m_time > p_rhs.m_time;
	}
};

class Node
{
	Node* m_father;
	Node* m_leftSon;
	Node* m_rightSon;
	int m_rootDistance;


	Node(Node* p_left, Node* p_right)
		:m_father(NULL), m_leftSon(p_left), m_rightSon(p_right), m_rootDistance(-1){}

public:
	Node()
		:m_father(NULL), m_leftSon(NULL), m_rightSon(NULL), m_rootDistance(-1){}

	bool isRoot(){return m_father==NULL;}


	void computeRootDistances( int distance )
	{
		m_rootDistance = distance;
		if(m_leftSon)
			m_leftSon->computeRootDistances( distance + 1 );
		if(m_rightSon)
			m_rightSon->computeRootDistances( distance + 1 );
	}

	static int getCombinationTime( Node* p_left, Node* p_right)
	{
		while( p_left->m_rootDistance < p_right->m_rootDistance )
			p_right = p_right->m_father;
		while( p_right->m_rootDistance < p_left->m_rootDistance )
			p_left = p_left->m_father;
		while( p_left != p_right )
		{
			p_right = p_right->m_father;
			p_left = p_left->m_father;
		}
		if( p_left == NULL )
			return -1;
		return p_left->m_rootDistance;
	}

	static Node* merge(Node* p_left, Node* p_right)
	{
		p_left->m_father = new Node(p_left, p_right);
		p_right->m_father = p_left->m_father;
		return p_right->m_father;
	}
};



void scanAndInitialize()
{
	scanf("%d %d %d", &N, &M, &K);
	Reactions = new Reaction[K];
	int from, to;
	Node* VialCopy[MAX_NUM];
	for(unsigned i = 0; i < N; ++i)
	{
		scanf("%d", &Vol[i]);
		Vial[i] = new Node();
		VialCopy[i] = Vial[i];
	}

	for(unsigned i = 0; i < M; ++i)
	{
		scanf("%d %d", &from, &to);
		from--;
		to--;
		Vial[ to ] = Node::merge( Vial[from], Vial[to]); 
	}

	for(unsigned i = 0; i < N; ++i)
	{
		if( Vial[i]->isRoot() )
			Vial[i]->computeRootDistances(0);
		Vial[i] = VialCopy[i];
	}

}



void scanAnalizeReactions()
{
	int a, b;
	for(unsigned i = 0; i < K; ++i)
	{
		scanf("%d %d", &a, &b);
		a--;
		b--;
		Reactions[i] = Reaction(a, b, Node::getCombinationTime(Vial[a], Vial[b]) );
	}
	stable_sort( Reactions, Reactions + K );
}

LLD computeSedimentVol()
{
	LLD sedimentVol = 0;
	int tmp;
	for(unsigned i = 0; i < K; ++i)
	{
		if( Reactions[i].m_time != -1 )
		{
			tmp = min( Vol[ Reactions[i].m_a ], Vol[ Reactions[i].m_b ] );
			Vol[ Reactions[i].m_a ] -= tmp;
			Vol[ Reactions[i].m_b ] -= tmp;
			sedimentVol += (LLD)tmp*2L;
		}
	}
	return sedimentVol;
}




int main()
{
	scanAndInitialize();
	scanAnalizeReactions();

	printf( "%lld\n", computeSedimentVol() );
	
	return 0;
}