#nullable enable

using System.Numerics;

void Run()
{
    var n = Int();
    var m = Int();
    var edges = new (int, int, int)[m];
    for (var i = 0; i < m; i++)
    {
        var a = Int() - 1;
        var b = Int() - 1;
        var c = Int();
        edges[i] = (-c, a, b);
    }
    Array.Sort(edges);
    var uf = new UnionFind(n);
    var ans = 0L;
    foreach (var (nc, a, b) in edges)
    {
        var c = -nc;
        if (uf.Find(a) != uf.Find(b))
        {
            ans += c;
            uf.Union(a, b);
        }
    }
    Out(ans * 2);
}

#region
AtCoderIO _io_;
var _backend_ = new StandardIOBackend();
_io_ = new(){ Backend = _backend_ };
Run();
_backend_.Flush();

string String() => _io_.Next();
int Int() => int.Parse(String());
void Out(object? x, string? sep = null) => _io_.Out(x, sep);

class AtCoderIO
{
    public required StandardIOBackend Backend { get; init; }

    Memory<string> _input = Array.Empty<string>();
    int _iter = 0;
    public string Next()
    {
        while (_iter >= _input.Length) (_input, _iter) = (Backend.ReadLine().Split(' '), 0);
        return _input.Span[_iter++];
    }

    public void Out(object? x, string? separator = null)
    {
        if (x == null) return;
        separator ??= Environment.NewLine;
        if (x is System.Collections.IEnumerable a and not string)
        {
            var objects = a.Cast<object>();
            if (separator == Environment.NewLine && !objects.Any()) return;
            x = string.Join(separator, objects);
        }
        Backend.WriteLine(x);
    }
}

class StandardIOBackend
{
    readonly StreamReader _sr = new(Console.OpenStandardInput());
    readonly StreamWriter _sw = new(Console.OpenStandardOutput()) { AutoFlush = false };
    public string ReadLine() => _sr.ReadLine()!;
    public void WriteLine(object? value) => _sw.WriteLine(value);
    public void Flush() => _sw.Flush();
}
#endregion

static class Extensions
{
    public static T[] Repeat<T>(this int time, Func<T> F) => Enumerable.Range(0, time).Select(_ => F()).ToArray();
}

class UnionFind
{
    (int parent, int edgeCount)[] Verticals { get; set; }
    bool EnabledUndo { get; init; }
    Stack<(int v, (int parent, int edges))> Histories { get; init; }

    public UnionFind(int verticals, bool enableUndo = false)
    {
        Verticals = new (int, int)[verticals];
        for (int i = 0; i < verticals; i++) Verticals[i] = (-1, 0);
        Histories = new();
        EnabledUndo = enableUndo;
    }

    public int Union(int x, int y)
    {
        (x, y) = (Find(x), Find(y));
        var (sx, sy) = (Size(x), Size(y));
        if (sx < sy) (x, y, sy) = (y, x, sx);
        var (nx, ny) = (Verticals[x], Verticals[y]);
        Histories.Push((x, nx));
        Histories.Push((y, ny));
        if (x == y) nx.edgeCount += 1;
        else
        {
            ny.parent = x;
            nx.parent -= sy;
            nx.edgeCount += ny.edgeCount + 1;
        }
        (Verticals[y], Verticals[x]) = (ny, nx);
        return x;
    }

    public int Find(int x)
    {
        var pid = Verticals[x].parent;
        if (pid < 0) return x;
        var aid = Find(pid);
        if (!EnabledUndo) Verticals[x].parent = aid;
        return aid;
    }
    public int Size(int x) => -Verticals[Find(x)].parent;
    public int EdgeCount(int x) => Verticals[Find(x)].edgeCount;

    public bool Undo()
    {
        if (!EnabledUndo || Histories.Count == 0) return false;
        for (var i = 0; i < 2; i++)
        {
            var (v, h) = Histories.Pop();
            Verticals[v] = h;
        }
        return true;
    }
}