import java.io.BufferedReader;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.ListIterator;
import java.util.Map.Entry;
import java.util.PriorityQueue;
import java.util.Scanner;
import java.util.StringTokenizer;
import java.util.TreeMap;
import java.util.TreeSet;

import javax.swing.text.Segment;

public class Main {

	public static long Chu_Liu_Edmonds(final int V, int root, ArrayList<HashMap<Integer, Long>> rev_adj) {
		// ??????????????\???????°???????????????????????±???????
		long[] min_costs = new long[V];
		int[] min_pars = new int[V];
		min_costs[root] = 0;
		min_pars[root] = root;
		//System.out.println(rev_adj);

		for (int start = 0; start < V; start++) {
			if (start == root) { continue; }
			long min_cost = -1;
			int min_par = -1;

			for (final Entry<Integer, Long> entry : rev_adj.get(start).entrySet()) {
				final int par = entry.getKey();
				final long cost = entry.getValue();

				if (min_cost < 0 || min_cost > cost) {
					min_par = par;
					min_cost = cost;
				}
			}

			min_pars[start] = min_par;
			min_costs[start] = min_cost;
		}

		// ????????? 1 ???????????????
		boolean has_cycle = false;
		int[] belongs = new int[V];
		for(int i = 0; i < V; i++){ belongs[i] = i; }
		
		boolean[] is_cycle = new boolean[V];
		
		for (int start = 0; start < V; start++) {
			if(min_pars[start] < 0){ continue; }
			
			boolean[] used = new boolean[V];		
			int curr = start;
			while (!used[curr] && min_pars[curr] != curr) {
				used[curr] = true;
				curr = min_pars[curr];
			}
			
			// ??????????????\?????????
			if (curr != root) {
				belongs[curr] = V;
				is_cycle[curr] = true;
				
				int cycle_start = curr;
				while (min_pars[curr] != cycle_start) {
					belongs[min_pars[curr]] = V; 
					is_cycle[min_pars[curr]] = true;
					curr = min_pars[curr];
				}
				
				has_cycle = true;
				
				break;
			}else{
				// ????????¨??¢?????????
			}
		}
		//System.out.println(V + " " + Arrays.toString(belongs));
		
		if(!has_cycle){ 
			long sum = 0;
			for(int i = 0; i < V; i++){
				sum += Math.max(0, min_costs[i]);
			}
			
			return sum;
		}
		
		
		long cycle_sum = 0;
		for(int i = 0; i < V; i++){
			if(!is_cycle[i]){ continue; }
			cycle_sum += min_costs[i];
		}
		
		ArrayList<HashMap<Integer, Long>> next_rev_adj = new ArrayList<HashMap<Integer, Long>>();
		for(int i = 0; i <= V; i++){
			next_rev_adj.add(new HashMap<Integer, Long>());
		}
		for(int start = 0; start < V; start++){
			final int start_belongs = belongs[start];
			for(final Entry<Integer, Long> entry : rev_adj.get(start).entrySet()){
				final int prev = entry.getKey();
				final int prev_belongs = belongs[prev];
				
				
				if(start_belongs == prev_belongs){ continue; }
				else if(is_cycle[start]){
					if(!next_rev_adj.get(start_belongs).containsKey(prev_belongs)){
						next_rev_adj.get(start_belongs).put(prev_belongs, rev_adj.get(start).get(prev) - min_costs[start]);
					}else{
						final long old_cost = next_rev_adj.get(start_belongs).get(prev_belongs);
						next_rev_adj.get(start_belongs).put(prev_belongs, Math.min(old_cost, rev_adj.get(start).get(prev) - min_costs[start]));
					}
				}else{
					if(!next_rev_adj.get(start_belongs).containsKey(prev_belongs)){
						next_rev_adj.get(start_belongs).put(prev_belongs, rev_adj.get(start).get(prev));
					}else{
						final long old_cost = next_rev_adj.get(start_belongs).get(prev_belongs);
						next_rev_adj.get(start_belongs).put(prev_belongs, Math.min(old_cost, rev_adj.get(start).get(prev)));
					}
				}
			}
		}
		
		//System.out.println(cycle_sum);
		return cycle_sum + Chu_Liu_Edmonds(V + 1, root, next_rev_adj);
	}

	public static void main(String[] args) throws IOException {
		try (Scanner sc = new Scanner(System.in)) {
			final int V = sc.nextInt();
			final int E = sc.nextInt();
			final int S = sc.nextInt();

			ArrayList<HashMap<Integer, Long>> fwd_adj = new ArrayList<HashMap<Integer, Long>>();
			ArrayList<HashMap<Integer, Long>> rev_adj = new ArrayList<HashMap<Integer, Long>>();
			for (int i = 0; i < V; i++) {
				fwd_adj.add(new HashMap<Integer, Long>());
			}
			for (int i = 0; i < V; i++) {
				rev_adj.add(new HashMap<Integer, Long>());
			}

			for (int i = 0; i < E; i++) {
				final int s = sc.nextInt();
				final int t = sc.nextInt();
				final long w = sc.nextLong();

				if (!fwd_adj.get(s).containsKey(t)) {
					fwd_adj.get(s).put(t, w);
				} else {
					fwd_adj.get(s).put(t, Math.min(w, fwd_adj.get(s).get(t)));
				}

				if (!rev_adj.get(t).containsKey(s)) {
					rev_adj.get(t).put(s, w);
				} else {
					rev_adj.get(t).put(s, Math.min(w, rev_adj.get(t).get(s)));
				}
			}

			System.out.println(Chu_Liu_Edmonds(V, S, rev_adj));
		}
	}

	public static class Scanner implements Closeable {
		private BufferedReader br;
		private StringTokenizer tok;

		public Scanner(InputStream is) throws IOException {
			br = new BufferedReader(new InputStreamReader(is));
		}

		private void getLine() throws IOException {
			while (!hasNext()) {
				tok = new StringTokenizer(br.readLine());
			}
		}

		private boolean hasNext() {
			return tok != null && tok.hasMoreTokens();
		}

		public String next() throws IOException {
			getLine();
			return tok.nextToken();
		}

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

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

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

		public int[] nextIntArray(int n) throws IOException {
			final int[] ret = new int[n];
			for (int i = 0; i < n; i++) {
				ret[i] = this.nextInt();
			}
			return ret;
		}

		public long[] nextLongArray(int n) throws IOException {
			final long[] ret = new long[n];
			for (int i = 0; i < n; i++) {
				ret[i] = this.nextLong();
			}
			return ret;
		}

		public void close() throws IOException {
			br.close();
		}
	}
}

Measured memory_bytes: 28700