using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.IO;
using System.Text;
using System.Linq;

using E = System.Linq.Enumerable;
using CostType = System.Int64;
using System.Threading;

internal partial class Solver {
    public void Run() {
        var t = ni();
        var n = ni();
        var m = ni();

        var graph = new WeightedDirectedGraph(n);
        for (int i = 0; i < m; i++) {
            var a = ni() - 1;
            var b = ni() - 1;
            var w = ni();
            if (t == 0) {
                graph.AddUndirectedEdge(a, b, w);
            } else {
                graph.AddDirectedEdge(a, b, w);
            }
        }

        if (t == 1) {
            var d = E.Range(0, n)
                .Select(i => graph.Dijkstra(i))
                .ToArray();
            long ans = long.MaxValue;
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < i; j++) {
                    if (d[i][j] == long.MaxValue || d[j][i] == long.MaxValue) continue;
                    ans = Math.Min(ans, d[i][j] + d[j][i]);
                }
            }
            if (ans == long.MaxValue) ans = -1;
            cout.WriteLine(ans);
        } else {
            long ans = long.MaxValue;

            for (int i = 0; i < n; i++) {
                foreach (var edge in graph[i]) {
                    if (edge.From < edge.To) {
                        ans = Math.Min(ans, FindMinLoop(graph, edge.From, edge.To, edge.Cost));
                    }
                }
            }

            if (ans == long.MaxValue) ans = -1;
            cout.WriteLine(ans);
        }

    }

    public static long FindMinLoop(WeightedDirectedGraph graph, int start, int end, long edgeCost) {
        var n = graph.VertexCount;
        var visited = new bool[n];
        var pq = new PriorityQueue<(long Cost, int Pos)>();

        pq.Enqueue((0, start));

        while (pq.Count > 0) {
            var current = pq.Dequeue();
            if (visited[current.Pos]) continue;
            visited[current.Pos] = true;

            if (current.Pos == end) return current.Cost + edgeCost;

            foreach (var edge in graph[current.Pos]) {
                if (visited[edge.To]) continue;
                if (edge.From == start && edge.To == end) continue;
                pq.Enqueue((current.Cost + edge.Cost, edge.To));
            }
        }

        return long.MaxValue;
    }
}


public class ShorestPathInfo {
    private readonly CostType[] _dist;
    private readonly int[] _prev;
    public ShorestPathInfo(CostType[] dist, int[] prev) {
        _dist = dist;
        _prev = prev;
    }
    public CostType this[int index] {
        get { return _dist[index]; }
    }
    public IEnumerable<int> GetPath(int to) {
        int current = to;
        var path = new List<int>();
        do {
            path.Add(current);
            current = _prev[current];
        } while (current >= 0);
        path.Reverse();
        return path;
    }
}


public class PriorityQueue<T> {
    private T[] _array = new T[128];
    private int _size = 0;
    private readonly Comparison<T> _compare;

    public PriorityQueue() {
        _compare = Comparer<T>.Default.Compare;
    }

    public PriorityQueue(Comparison<T> comp) {
        _compare = comp;
    }

    public int Count { get { return _size; } }

    private void Swap(int a, int b) {
        var t = _array[a];
        _array[a] = _array[b];
        _array[b] = t;
    }

    private void Expand() {
        var newlist = new T[_array.Length << 1];
        Array.Copy(_array, newlist, _array.Length);
        _array = newlist;
    }

    public bool Any() {
        return _size > 0;
    }

    public void Enqueue(T newValue) {
        int pos = ++_size;
        if (_size >= _array.Length) {
            Expand();
        }
        _array[pos] = newValue;
        while (pos > 1) {
            int parent = pos >> 1;
            if (_compare(_array[parent], _array[pos]) > 0) {
                Swap(parent, pos);
                pos = parent;
            } else {
                break;
            }
        }
    }

    public T Peek() {
        return _array[1];
    }

    public T Dequeue() {
        var top = _array[1];
        int pos = 1;
        _array[pos] = _array[_size--];
        while ((pos << 1) <= _size) {
            int left = pos << 1;
            int right = left | 1;
            int next = left;
            if (right <= _size && _compare(_array[left], _array[right]) > 0) {
                next = right;
            }
            if (_compare(_array[pos], _array[next]) > 0) {
                Swap(next, pos);
                pos = next;
            } else {
                break;
            }
        }

        return top;
    }
};

public static partial class ShortestPathExtension {
    struct Data {
        public int pos { get; set; }
        public int prev { get; set; }
        public CostType cost;
    }
    public static ShorestPathInfo Dijkstra(this WeightedDirectedGraph graph, int start) {
        var n = graph.VertexCount;
        var dist = Enumerable.Repeat(CostType.MaxValue, n).ToArray();
        var prev = Enumerable.Repeat(-1, n).ToArray();
        var visited = new bool[n];
        var pq = new PriorityQueue<Data>((d1, d2) => d1.cost.CompareTo(d2.cost));
        pq.Enqueue(new Data { pos = start, prev = -1 });
        while (pq.Count > 0) {
            var current = pq.Dequeue();
            if (visited[current.pos]) continue;
            visited[current.pos] = true;
            dist[current.pos] = current.cost;
            prev[current.pos] = current.prev;
            foreach (var edge in graph[current.pos]) {
                if (visited[edge.To]) continue;
                if (dist[edge.To] > current.cost + edge.Cost) {
                    dist[edge.To] = current.cost + edge.Cost;
                    pq.Enqueue(new Data { pos = edge.To, prev = edge.From, cost = current.cost + edge.Cost });
                }
            }
        }
        return new ShorestPathInfo(dist, prev);
    }
}


public struct WeightedEdge {
    public int From { get; set; }
    public int To { get; set; }
    public CostType Cost { get; set; }
}

public class WeightedDirectedGraph {
    private readonly List<WeightedEdge>[] _adj;
    public WeightedDirectedGraph(int n) {
        _adj = Enumerable.Range(0, n).Select(_ => new List<WeightedEdge>()).ToArray();
    }

    public void AddDirectedEdge(int from, int to, CostType cost) {
        _adj[from].Add(new WeightedEdge { From = from, To = to, Cost = cost });
    }

    public void AddUndirectedEdge(int from, int to, CostType cost) {
        _adj[from].Add(new WeightedEdge { From = from, To = to, Cost = cost });
        _adj[to].Add(new WeightedEdge { From = to, To = from, Cost = cost });
    }

    public IEnumerable<WeightedEdge> this[int index] {
        get { return _adj[index]; }
    }

    public int VertexCount { get { return _adj.Length; } }
}

// PREWRITEN CODE BEGINS FROM HERE

static public class StringExtensions {
    static public string JoinToString<T>(this IEnumerable<T> source, string separator = " ") {
        return string.Join(separator, source);
    }
}

internal partial class Solver : Scanner {
    static readonly int? StackSizeInMebiByte = null; //50;
    public static void StartAndJoin(Action action, int maxStackSize) {
        var thread = new Thread(new ThreadStart(action), maxStackSize);
        thread.Start();
        thread.Join();
    }

    public static void Main() {
#if LOCAL
        byte[] inputBuffer = new byte[1000000];
        var inputStream = Console.OpenStandardInput(inputBuffer.Length);
        using (var reader = new StreamReader(inputStream, Console.InputEncoding, false, inputBuffer.Length)) {
            Console.SetIn(reader);
            new Solver(Console.In, Console.Out).Run();
        }
#else
        Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });
        if (StackSizeInMebiByte.HasValue) {
            StartAndJoin(() => new Solver(Console.In, Console.Out).Run(), StackSizeInMebiByte.Value * 1024 * 1024);
        } else {
            new Solver(Console.In, Console.Out).Run();
        }
        Console.Out.Flush();
#endif
    }

#pragma warning disable IDE0052
    private readonly TextReader cin;
    private readonly TextWriter cout;
    private readonly TextWriter cerr;
#pragma warning restore IDE0052

    public Solver(TextReader reader, TextWriter writer)
        : base(reader) {
        cin = reader;
        cout = writer;
        cerr = Console.Error;
    }

    public Solver(string input, TextWriter writer)
        : this(new StringReader(input), writer) {
    }

#pragma warning disable IDE1006
#pragma warning disable IDE0051
    private int ni() { return NextInt(); }
    private int[] ni(int n) { return NextIntArray(n); }
    private long nl() { return NextLong(); }
    private long[] nl(int n) { return NextLongArray(n); }
    private double nd() { return NextDouble(); }
    private double[] nd(int n) { return NextDoubleArray(n); }
    private string ns() { return Next(); }
    private string[] ns(int n) { return NextArray(n); }
#pragma warning restore IDE1006
#pragma warning restore IDE0051
}

#if DEBUG
internal static class LinqPadExtension {
    public static string TextDump<T>(this T obj) {
        if (obj is IEnumerable) return (obj as IEnumerable).Cast<object>().JoinToString().Dump();
        else return obj.ToString().Dump();
    }
    public static T Dump<T>(this T obj) {
        return LINQPad.Extensions.Dump(obj);
    }
}
#endif

public class Scanner {
    private readonly TextReader Reader;
    private readonly CultureInfo ci = CultureInfo.InvariantCulture;

    private readonly char[] buffer = new char[2 * 1024];
    private int cursor = 0, length = 0;
    private string Token;
    private readonly StringBuilder sb = new StringBuilder(1024);

    public Scanner()
        : this(Console.In) {
    }

    public Scanner(TextReader reader) {
        Reader = reader;
    }

    public int NextInt() { return checked((int)NextLong()); }
    public long NextLong() {
        var s = Next();
        long r = 0;
        int i = 0;
        bool negative = false;
        if (s[i] == '-') {
            negative = true;
            i++;
        }
        for (; i < s.Length; i++) {
            r = r * 10 + (s[i] - '0');
#if DEBUG
            if (!char.IsDigit(s[i])) throw new FormatException();
#endif
        }
        return negative ? -r : r;
    }
    public double NextDouble() { return double.Parse(Next(), ci); }
    public string[] NextArray(int size) {
        string[] array = new string[size];
        for (int i = 0; i < size; i++) {
            array[i] = Next();
        }

        return array;
    }
    public int[] NextIntArray(int size) {
        int[] array = new int[size];
        for (int i = 0; i < size; i++) {
            array[i] = NextInt();
        }

        return array;
    }

    public long[] NextLongArray(int size) {
        long[] array = new long[size];
        for (int i = 0; i < size; i++) {
            array[i] = NextLong();
        }

        return array;
    }

    public double[] NextDoubleArray(int size) {
        double[] array = new double[size];
        for (int i = 0; i < size; i++) {
            array[i] = NextDouble();
        }

        return array;
    }

    public string Next() {
        if (Token == null) {
            if (!StockToken()) {
                throw new Exception();
            }
        }
        var token = Token;
        Token = null;
        return token;
    }

    public bool HasNext() {
        if (Token != null) {
            return true;
        }

        return StockToken();
    }

    private bool StockToken() {
        while (true) {
            sb.Clear();
            while (true) {
                if (cursor >= length) {
                    cursor = 0;
                    if ((length = Reader.Read(buffer, 0, buffer.Length)) <= 0) {
                        break;
                    }
                }
                var c = buffer[cursor++];
                if (33 <= c && c <= 126) {
                    sb.Append(c);
                } else {
                    if (sb.Length > 0) break;
                }
            }

            if (sb.Length > 0) {
                Token = sb.ToString();
                return true;
            }

            return false;
        }
    }
}