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#include <cstdio>
#include <algorithm>
#include <vector>

#define st first
#define nd second

const int MAXN = 200005, MAXK = 500005;
int n,m,k,realK,firstRoot,maxTreeHeight,maxSteps,degout[MAXN],nextRoot[MAXN],
	used[MAXN],treeNo[MAXN],level[MAXN],p[20][MAXN],activeOrder[MAXK],
	costToParent[MAXN],connectionStep[MAXK];
long long weight[MAXN];
std::pair<int,int> active[MAXK];
std::vector< std::pair<int,int> > graph[MAXN];

void init();
void dfs(int,int,int);
bool comp(int,int);
void calcConnSteps();

int main()
{
	scanf("%d%d%d", &n, &m, &k);
	for(int i = 0; i < n; ++i)
		scanf("%lld", &weight[i]);
	for(int i = 0; i < m; ++i)
	{
		int a,b;
		scanf("%d%d", &a, &b);
		a--; b--;
		degout[a]++;
		//graph[a].push_back(std::make_pair(b,i)); // chyba niepotrzebne
		graph[b].push_back(std::make_pair(a,i));
	}
	//printf("graph created\n");
	init();
	//printf("initialization complete\n");
	realK = 0;
	for(int i = 0; i < k; ++i)
	{
		int a,b;
		scanf("%d%d", &a, &b);
		a--; b--;
		if(treeNo[a] == treeNo[b])
			active[realK++] = std::make_pair(a,b);
	}
	//printf("active filter complete\n");

	calcConnSteps();

	//printf("steps calculation complete\n");
/*
	printf("Active have steps:\n");
	for(int i = 0; i < realK; ++i)
		printf("[%d,%d]: %d\n", active[i].st+1, active[i].nd+1, connectionStep[i]);
*/
	std::sort(activeOrder,activeOrder+realK,comp);

	//printf("sort active things complete\n");
/*
	printf("sorted: ");
	for(int i = 0; i < realK; ++i)
		printf("(%d,%d) ", active[activeOrder[i]].st+1, active[activeOrder[i]].nd+1);
	printf("\n");
*/
	long long result = 0;
	for(int i = 0; i < realK; ++i)
	{
		long long reaction = std::min(weight[active[activeOrder[i]].st],weight[active[activeOrder[i]].nd]);
		
		weight[active[activeOrder[i]].st] -= reaction;
		weight[active[activeOrder[i]].nd] -= reaction;
		result += 2*reaction;
	}

	printf("%lld\n", result);
}

void init()
{
	for(int i = 0; i < k; ++i)
		activeOrder[i] = i;

	firstRoot = -1;
	for(int i = n-1; i >= 0; --i)
	{
		nextRoot[i] = firstRoot;
		if(degout[i] == 0) firstRoot = i;
	}
	
	int currTree = firstRoot;
	while(currTree != -1)
	{
		//printf("tree in root %d\n", currTree);
		dfs(currTree,currTree,0);
		//printf("dfs part done\n");
		p[0][currTree] = currTree;
		currTree = nextRoot[currTree];
	}
	//printf("ok\n");
	int pow2 = 1, iterations = 0;
	while(pow2 < maxTreeHeight)
		{ pow2 *= 2; iterations++; }
	maxSteps = iterations;
	//printf("maxSteps: %d\n", maxSteps);

	for(int i = 1; i < maxSteps; ++i)
		for(int j = 0; j < n; ++j)
			p[i][j] = p[i-1][p[i-1][j]];
	//printf("p array ready\n");
}

void dfs(int v, int treeMark, int depth)
{
	level[v] = depth;
	used[v] = true;
	maxTreeHeight = std::max(maxTreeHeight,depth);
	treeNo[v] = treeMark;
	for(int i = 0; i < graph[v].size(); ++i)
	{
		if(used[graph[v][i].st]) continue;
		p[0][graph[v][i].st] = v;
		costToParent[graph[v][i].st] = graph[v][i].nd;
		dfs(graph[v][i].st,treeMark,depth+1);
	}
}

int equalize(int v, int diff)
{
	int node = v;
	for(int i = 0; i < maxSteps; ++i)
		if((1<<i) & diff)
			node = p[i][node];
	
	return node;
}

int LCA(int a, int b, int& nodeA, int& nodeB)
{
	nodeA = a, nodeB = b;
	int diff = std::abs(level[a]-level[b]);
	if(level[a] < level[b]) nodeB = equalize(nodeB,diff);
	else if(level[a] > level[b]) nodeA = equalize(nodeA,diff);

	if(nodeA == nodeB) return nodeA;

	for(int i = maxSteps; i >= 0; --i)
	{
		if(p[i][nodeA] != p[i][nodeB])
			{ nodeA = p[i][nodeA]; nodeB = p[i][nodeB]; }
	}

	if(p[0][nodeA] != p[0][nodeB]) printf("Something's wrong...\n");
	return p[0][nodeA];
}

bool isOnPath(int a, int b, int lca)
{
	if(lca == a || lca == b) return true;
	return false;
}

void calcConnSteps()
{
	int tmpNodeSt, tmpNodeNd, tmp;
	for(int i = 0; i < realK; ++i)
	{
		int lca = LCA(active[i].st,active[i].nd,tmpNodeSt,tmpNodeNd);
		//printf("found lca(%d,%d): %d\n", active[i].st+1, active[i].nd+1, lca+1);
		if(isOnPath(active[i].st,active[i].nd,lca))
		{
			if(active[i].st == lca)
				tmp = equalize(active[i].nd, std::abs(level[active[i].st]-level[active[i].nd])-1);
			else
				tmp = equalize(active[i].st, std::abs(level[active[i].st]-level[active[i].nd])-1);
			connectionStep[i] = costToParent[tmp];
		}
		else connectionStep[i] = std::max(costToParent[tmpNodeSt],costToParent[tmpNodeNd]);
	}
}

bool comp(int a, int b)
{
	if(connectionStep[a] == connectionStep[b])
		return a < b;
	return connectionStep[a] < connectionStep[b];
}