// Java program for the above approach
import java.util.*;
// Implementation of DSU
class UnionFind {
    private int[] parent;
    private int[] rank;
    private int time;
    private int count;

    public UnionFind(int N)
    {
        parent = new int[N];
        rank = new int[N];
        time = 0;
        count = N;

        for (int i = 0; i < N; i++) {
            parent[i] = i;
            rank[i] = 1;
        }
    }

    public int find(int node)
    {
        if (node == parent[node])
            return node;
        return parent[node] = find(parent[node]);
    }

    public void performUnion(int u, int v, int updatedTime)
    {
        if (count == 1)
            return;

        int rootX = find(u);
        int rootY = find(v);

        if (rootX != rootY) {
            if (rank[rootX] < rank[rootY]) {
                parent[rootX] = rootY;
            }
            else if (rank[rootX] > rank[rootY]) {
                parent[rootY] = rootX;
            }
            else {
                parent[rootX] = rootY;
                rank[rootY] += 1;
            }

            time = updatedTime;
            count--;
        }
    }

    public int getCount() { return count; }

    public int getTime() { return time; }
}

class Main {
    private static int earliestTime(List<int[]> arr, int N)
    {
        arr.sort(Comparator.comparingInt(a -> a[2]));

        UnionFind unionFind = new UnionFind(N);

        for (int[] it : arr) {
            unionFind.performUnion(it[0], it[1], it[2]);
        }

        return unionFind.getCount() == 1
            ? unionFind.getTime()
            : -1;
    }

    public static void main(String[] args)
    {
        int N = 6;
        List<int[]> arr
            = Arrays.asList(new int[][] { { 0, 1, 4 },
                                        { 3, 4, 5 },
                                        { 2, 3, 14 },
                                        { 1, 5, 24 },
                                        { 2, 4, 12 },
                                        { 0, 3, 42 },
                                        { 1, 2, 41 },
                                        { 4, 5, 11 } });

        System.out.println(earliestTime(arr, N));
    }
}