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import java.io.BufferedOutputStream;
import java.io.DataInputStream;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.PriorityQueue;

public class fio {

	private static Parser input = new Parser(System.in);
	private static BufferedOutputStream output = new BufferedOutputStream(
			System.out);

	static final int NEVER_BEEN_THERE = -1;

	static List<List<Edge>> tree = new ArrayList<>();
	static List<List<Interact>> reactions = new ArrayList<>();
	static int[] elixir;
	static int[] dfs;
	static boolean[] isUsed;

	static int dfsCount;
	static long result;
	static PriorityQueue<React> que = new PriorityQueue<React>();

	public static void main(String[] args) throws Exception {

		int n = input.nextInt();
		int m = input.nextInt();
		int k = input.nextInt();

		elixir = new int[n];
		for (int i = 0; i < n; i++) {
			elixir[i] = input.nextInt();
		}

		isUsed = new boolean[n];
		dfs = new int[n];
		for (int i = 0; i < n; i++) {
			dfs[i] = NEVER_BEEN_THERE;
		}

		for (int i = 0; i < n; i++) {
			tree.add(new ArrayList<Edge>());
			reactions.add(new ArrayList<Interact>());
		}

		for (int i = 0; i < m; i++) {
			int a = input.nextInt();
			int b = input.nextInt();

			tree.get(b - 1).add(new Edge(a - 1, i));
			isUsed[a - 1] = true;
		}

		for (int i = 0; i < n; i++) {
			Collections.sort(tree.get(i));
		}

		for (int i = 0; i < k; i++) {
			int c = input.nextInt();
			int d = input.nextInt();

			reactions.get(c - 1).add(new Interact(d - 1, i));
			reactions.get(d - 1).add(new Interact(c - 1, i));
		}

		for (int i = 0; i < n; i++) {
			if (!isUsed[i]) {
				pleaseTheLord(i);
			}
		}

		output.write((result + "\n").getBytes());
		output.flush();
	}

	private static void pleaseTheLord(int v) {
		dfs[v] = dfsCount++;

		List<React> curReacts;
		for (Edge edge : tree.get(v)) {
			pleaseTheLord(edge.v);

			curReacts = new ArrayList<>();
			while (!que.isEmpty() && que.peek().ifso >= dfs[v]) {
				curReacts.add(que.remove());
			}

			Collections.sort(curReacts, new PriorityComparator());
			for (React react : curReacts) {
				int sediment = Math.min(elixir[react.with], elixir[react.what]);
				result += sediment;
				elixir[react.with] -= sediment;
				elixir[react.what] -= sediment;
				
				result += sediment;
			}
		}

		for (Interact interact : reactions.get(v)) {
			if (dfs[interact.with] != NEVER_BEEN_THERE) {
				que.add(new React(v, interact.with, interact.priority,
						dfs[interact.with]));
			}
		}

	}

}

class Edge implements Comparable<Edge> {
	int v;
	int time;

	public Edge(int v, int time) {
		super();
		this.v = v;
		this.time = time;
	}

	@Override
	public int compareTo(Edge o) {
		return Integer.compare(time, o.time);
	}
}

class Interact {

	int with;
	int priority;

	public Interact(int with, int priority) {

		this.with = with;
		this.priority = priority;
	}
}

class React extends Interact implements Comparable<React> {
	int what;
	int ifso;

	public React(int what, int with, int priority, int ifso) {
		super(with, priority);
		this.what = what;
		this.ifso = ifso;
	}

	@Override
	public int compareTo(React o) {
		return Integer.compare(o.ifso, ifso);
	}

}

class PriorityComparator implements Comparator<React> {

	@Override
	public int compare(React o1, React o2) {
		return Integer.compare(o1.priority, o2.priority);
	}

}

class Parser {
	final private int BUFFER_SIZE = 1 << 16;

	private DataInputStream din;
	private byte[] buffer;
	private int bufferPointer, bytesRead;

	public Parser(InputStream in) {
		din = new DataInputStream(in);
		buffer = new byte[BUFFER_SIZE];
		bufferPointer = bytesRead = 0;
	}

	public int nextInt() throws Exception {
		int ret = 0;
		byte c = read();
		while (c <= ' ')
			c = read();
		boolean neg = c == '-';
		if (neg)
			c = read();
		do {
			ret = ret * 10 + c - '0';
			c = read();
		} while (c > ' ');
		if (neg)
			return -ret;
		return ret;
	}

	private void fillBuffer() throws Exception {
		bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
		if (bytesRead == -1)
			buffer[0] = -1;
	}

	private byte read() throws Exception {
		if (bufferPointer == bytesRead)
			fillBuffer();
		return buffer[bufferPointer++];
	}
}