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#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <set>
#include <unordered_set>
#include <unordered_map>
using namespace std;
#define REP(i,n) for(int i=1; i<=(n); ++i)
#define FOR(i,a,b) for(int i=(a); i!=(b); ++i)
#define FORE(it,t) for(auto& it: t)
typedef vector<int> vi;
#define pb push_back
typedef pair<int,int> pii;
#define st first
#define nd second
typedef unordered_map<int,int> hii;
typedef long long ll;
#define INF 1000000001
#define sz size()
#define ALL(t) (t).begin(),(t).end()
#define SC(a) scanf("%d", &a)
#define GET(a) int a; SC(a)
#define ISDEBUG 1
#define dprintf(...) if(ISDEBUG) \
	{printf("\033[31m"); printf(__VA_ARGS__); printf("\033[0m");}
template <class It> void dptab(It b, It e, const char* f="%d ")
	{if(ISDEBUG) {for(It it=b; it!=e; ++it) dprintf(f, *it); dprintf("\n"); }}
#define LH 20

int n, m, k;
ll osad;
vi amounts;


struct node {
	node* child[2];
	vector<pii> reactions;
	vector<node*> pars;
	int h;

	node(node* lchild=0, node* rchild=0) : child{lchild,rchild}, pars(LH), h(0) {}
	void niszcz() {
		FORE(ch, child) if(ch) ch->niszcz();
		FORE(r, reactions) {
			ll now = min(amounts[r.st], amounts[r.nd]);
			osad += 2*now;
			amounts[r.st] -= now;
			amounts[r.nd] -= now;			
		}
	}
	void dfs(node* par=0) {
		par = par? par : this;
		h = par->h+1;
		pars[0] = par;
		FOR(i,1,LH)
			pars[i] = pars[i-1]->pars[i-1];
		FORE(ch, child)
			if(ch) ch->dfs(this);
	}
	node* up(int i) {
		int k = 0;
		int power = 1;
		node* n = this;
		while(i) {
			if(i&power) {
				i -= power;
				n = n->pars[k];
			}
			++k;
			power *= 2;
		}
		return n;
	}
};

vector<node*> nodes, originals;

void build_lca() {
	FORE(node, nodes)
		if(node) node->dfs();
}

void add_reaction(int aid, int bid) {
	node *a = originals[aid], *b = originals[bid];
	if(a->pars.back() != b->pars.back()) return;
	if(a->h > b->h) a = a->up(a->h - b->h);
	if(b->h > a->h) b = b->up(b->h - a->h);
	for(int i=LH-1; i>=0; --i) {
		if(a->pars[i] != b->pars[i]) {
			a = a->pars[i];
			b = b->pars[i];
		}
	}
	a->pars[0]->reactions.pb({aid, bid});
}

ll niszcz() {
	FORE(node, nodes)
		if(node) node->niszcz();
	return osad;
}

int main() {
	scanf("%d%d%d", &n, &m, &k);
	nodes.resize(n+1);
	amounts.resize(n+1);
	REP(i,n) {
		SC(amounts[i]);
		nodes[i] = new node;
	}
	originals = nodes;
	REP(i,m) {
		GET(a); GET(b);
		nodes[b] = new node(nodes[a], nodes[b]);
		nodes[a] = 0;
	}
	build_lca();
	REP(i, k) {
		GET(a); GET(b);
		add_reaction(a, b);
	}
	printf("%lld\n", niszcz());
}