Binary Search

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.Queue;
import java.util.StringTokenizer;

/**
 * <b> Algorithm on Codeforces. Problem E div 2 </b> </br>
 *
 * @author Huynh Quang Thao
 *
 */
public class Main {

    public static void main(String[] args) throws Exception {
        Main main = new Main();
        main.run();
    }

    public void run() throws Exception {
        InputReader sc = null;

        sc = new InputReader(System.in);
        sc = new InputReader(new FileInputStream(new File("input.txt")));

        int ntestcase = sc.nextInt();
        while (ntestcase-- > 0) {
            int n = sc.nextInt();
            int m = sc.nextInt();
            int a = sc.nextInt() - 1;
            int b = sc.nextInt() - 1;

            ArrayList<ArrayList<Edge>> adjList = new ArrayList<ArrayList<Edge>>();
            for (int i = 0; i < n; i++) {
                ArrayList<Edge> neighbor = new ArrayList<Edge>();
                adjList.add(neighbor);
            }

            for (int i = 0; i < m; i++) {
                int u = sc.nextInt() - 1;
                int v = sc.nextInt() - 1;
                int w = sc.nextInt();
                adjList.get(u).add(new Edge(v, w));
                adjList.get(v).add(new Edge(u, w));
            }

            int left = 0;
            int right = 1000;
            while (left + 1 < right) {
                int mid = (left + right) / 2;
                if (dfs(a, b, adjList, mid))
                    left = mid;
                else
                    right = mid;
            }

            System.out.println(left);

        }
    }

    public boolean dfs(int s, int t, ArrayList<ArrayList<Edge>> adjList, int cap) {
        boolean[] check = new boolean[adjList.size()];
        Queue<Integer> queue = new LinkedList<Integer>();
        queue.add(s);
        while (!queue.isEmpty()) {
            int v = queue.poll();
            if (check[v])
                continue;
            check[v] = true;
            if (v == t)
                return true;
            for (int i = 0; i < adjList.get(v).size(); i++) {
                int u = adjList.get(v).get(i).u;
                int w = adjList.get(v).get(i).weight;
                if (cap <= w && !check[u])
                    queue.add(u);
            }
        }
        return false;
    }

    static class Edge {
        int u, weight;

        public Edge(int u, int weight) {
            this.u = u;
            this.weight = weight;
        }
    }

    static class InputReader {
        public BufferedReader reader;

        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream));
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                }
                catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

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

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

        public float nextFloat() {
            return Float.parseFloat(next());
        }

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

        public BigInteger nextBigInteger() {
            return new BigInteger(next());
        }

    }
}