import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.NoSuchElementException;
import java.util.*;
public class Main {
	ArrayList<Edge>[] graph;
	int V,E,R;
	private class Edge implements Comparable<Edge>{
		int to,cost;
		public Edge(int to,int cost){
			this.to =  to;
			this.cost = cost;
		}
		
		public int compareTo(Edge e){
			return this.cost - e.cost;
		}
	}
	
	@SuppressWarnings("unchecked")
    public void solve() {
		V = nextInt();
		E = nextInt();
		R = nextInt();
		graph = new ArrayList[V];
		for(int i = 0;i < V;i++){
			graph[i] = new ArrayList<Edge>();
		}
		for(int i = 0;i < E;i++){
			int s = nextInt();
			int t = nextInt();
			int w = nextInt();
			
			graph[s].add(new Edge(t,w));
		}
		int sum = 0;
		boolean[] used = new boolean[V];
		used[R] = true;
		PriorityQueue<Edge> pq = new PriorityQueue<Edge>();
		for(Edge e : graph[R]){
			pq.add(e);
		}
		while(pq.size() > 0){
			Edge e = pq.poll();
			if(used[e.to])continue;
			used[e.to] = true;
			sum += e.cost;
			for(Edge next : graph[e.to]){
				if(used[next.to])continue;
				pq.add(next);
			}
		}
		
		out.println(sum);
    }
 
	public static void main(String[] args) {
		out.flush();
		new Main().solve();
		out.close();
	}
		/* Input */
	private static final InputStream in = System.in;
	private static final PrintWriter out = new PrintWriter(System.out);
	private final byte[] buffer = new byte[2048];
	private int p = 0;
	private int buflen = 0;

	private boolean hasNextByte() {
		if (p < buflen)
			return true;
		p = 0;
		try {
			buflen = in.read(buffer);
		} catch (IOException e) {
			e.printStackTrace();
		}
		if (buflen <= 0)
			return false;
		return true;
	}

	public boolean hasNext() {
		while (hasNextByte() && !isPrint(buffer[p])) {
			p++;
		}
		return hasNextByte();
	}

	private boolean isPrint(int ch) {
		if (ch >= '!' && ch <= '~')
			return true;
		return false;
	}

	private int nextByte() {
		if (!hasNextByte())
			return -1;
		return buffer[p++];
	}

	public String next() {
		if (!hasNext())
			throw new NoSuchElementException();
		StringBuilder sb = new StringBuilder();
		int b = -1;
		while (isPrint((b = nextByte()))) {
			sb.appendCodePoint(b);
		}
		return sb.toString();
	}

	public int nextInt() {
		return Integer.parseInt(next());
	}

	public long nextLong() {
		return Long.parseLong(next());
	}

	public double nextDouble() {
		return Double.parseDouble(next());
	}
}