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#include<cstdio>
#include<vector>
#include<algorithm>
#include<map>
using namespace std;
typedef pair<int,int> pii;

int n; /// number of products
int m; /// number of operations
int k; /// number of reactions

vector<int> weight; /// weight of u
vector<int> number; /// number[u] = time when u is being used
vector< vector<int> > child; /// child[u] = { v : v -> u is an operation }

vector< vector<pii> > react; /// react[u] = { (v,i) : (u,v) is an reaction with number i }
vector<pii> reactions;       /// list of reactions (from the input)
vector<int> lca;

vector<int> anchestor; /// for Taran algorithm computing LCA; see http://en.wikipedia.org/wiki/Tarjan%27s_off-line_lowest_common_ancestors_algorithm
vector<int> colour;   ///  colours for Tarjan algorithm

vector<int> counter; /// Union-Find
vector<int> father;  /// Union-Find

vector< vector<int> >  lcaadj;
map< pii, int >        pathmax; // pathmax( (u,v) ) = max{ number[u1], number[u2], ..., number[un] } where u1,u2...,un is a path fromu to v.

vector< vector< pair<int,pii> > > todo; // todo[t] = vector of operation that should be done at the moment t

int Find(int a)
{
	return (father[a]==a) ? a : (father[a] = Find( father[a] ));
}
void Union(int a, int b)
{
	int fa = Find(a), fb = Find(b);
	if ( counter[fa] > counter[fb] ) swap(fa, fb);
	father[fa] = fb;
	counter[fb] += counter[fa];
}

int black;
void Tarjan(int u)
{
	//fprintf(stderr, "Tarjan(%d)\n", u); 
	anchestor[u] = u;
	for (int v : child[u])
	{
		Tarjan(v);
		Union(u,v);
		anchestor[ Find(u) ] = u;
	}
	colour[u] = black; // = true;
	for (pii V : react[u])
	{
		int v = V.first, nr = V.second;
		if ( colour[v]==black )
		{
			// LCA(u,v) is anchestor[ Find(v) ]
			// thus the reaction (u,v) will have place at number[ anchestor[Find(v)] ]
			int c = anchestor[Find(v)];
			//fprintf(stderr, "lca_tarjan(%d,%d)=%d\n", u,v,c);
			lca[nr] = c;
			if ( u!=c ) lcaadj[u].push_back(c);
			if ( v!=c ) lcaadj[v].push_back(c);
		}
	}
}

void dfs(int u)
{
	//fprintf(stderr, "dfs(%d)\n", u);
	for ( int v : lcaadj[u] ) pathmax[ pii(min(u,v), max(u,v)) ] = colour[v];
	for ( int v : child[u] )
	{
		colour[u] = number[v];
		dfs(v);
	}
}

int main()
{
	// read n,m,k
	scanf("%d%d%d", &n, &m, &k);
	
	// read the weights of products
	weight.resize(n+1);
	for (int u=1; u<=n; u++) scanf("%d", &weight[u]);
	
	// read the operations v -> u
	number.resize(n+1,n+1);
	child.resize(n+1);
	//vector<bool> root(n+1, true);
	for (int nr = 1; nr<=m; nr++)
	{
		int v, u;
		scanf("%d%d", &v, &u);
		child[u].push_back(v);
		number[v] = nr;
		//root[v] = false;
	}
	vector<int> roots;
	for (int u=1; u<=n; u++) if ( number[u] > n ) roots.push_back(u);
	
	// read the reactions
	react.resize(n+1);
	reactions.resize(k+1);
	for (int i=1; i<=k; i++)
	{
		int u, v;
		scanf("%d%d", &u, &v);
		if (u>v) swap(u,v);
		react[u].push_back(pii(v,i));
		react[v].push_back(pii(u,i));
		reactions[i] = pii(u,v);
	}
	
	// Union-Find initialization
	counter.resize(n+1, 1);
	father.resize(n+1);
	for (int u=0; u<=n; u++) { father[u] = u; }
	
	todo.resize(n+2);
	// Run Tarjan algorithm in every root
	colour.resize(n+1, 0);
	anchestor.resize(n+1);
	lca.resize(k+1);
	lcaadj.resize(n+1);
	black = 0;
	for (int r : roots)
	{
		black++;
		//fprintf(stderr, "Running Tarjan in the root %d\n", r);
		Tarjan(r);
	}
	anchestor.resize(0); counter.resize(0); father.resize(0);
	
	colour.resize(0); colour.resize(n+1, 0);
	for (int r : roots)	dfs(r);
	
	//for (int u=1; u<=n; u++) for (auto v : lcaadj[u]) fprintf(stderr, "lcaadj[%d][%d] with max=%d\n", u,v, (u==v)?0:pathmax[ pii(min(u,v), max(u,v)) ]);
	
	todo.resize(n+2);
	for (int nr=1; nr<=k; nr++)
	{
		int u = reactions[nr].first, v = reactions[nr].second;
		int c = lca[nr];
		//fprintf(stderr, "lca[%d:(%d,%d)]=%d\n", nr, u,v, c);
		int uc = (u==c) ? 0 : pathmax[ pii( min(u,c), max(u,c) ) ];
		int vc = (v==c) ? 0 : pathmax[ pii( min(v,c), max(v,c) ) ];
		int t = max(uc, vc);
		//fprintf(stderr, "todo[%d].push_back %d:(%d,%d)\n", t, nr, u,v);
		todo[t].push_back( make_pair(nr,pii(u,v)) );
	}
	
	long long totalResidue = 0;
	for ( int t = 1; t<=n+1; t++ )
	{
		sort( todo[t].begin(), todo[t].end() );
		for ( auto reaction : todo[t] )
		{
			int u = reaction.second.first, v = reaction.second.second;
			if ( weight[u] > weight[v] ) swap(u,v);
			//fprintf(stderr, "Reaction %d (%d grams) with %d (%d grams)\n", u, weight[u], v, weight[v]);
			totalResidue += weight[u];
			weight[v] -= weight[u];
			weight[u] = 0;
		}
	}
	printf("%lld\n", 2*totalResidue);
	return 0;
}