#include <bits/stdc++.h>
using namespace std;

#define CPP_STR(x) CPP_STR_I(x)
#define CPP_CAT(x, y) CPP_CAT_I(x, y)
#define CPP_STR_I(args...) #args
#define CPP_CAT_I(x, y) x##y

#define ASSERT(expr...) assert((expr))

using i8 = int8_t;
using u8 = uint8_t;
using i16 = int16_t;
using u16 = uint16_t;
using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;

using f32 = float;
using f64 = double;
// }}}

constexpr i64 INF = 1'010'000'000'000'000'017LL;

constexpr i64 MOD = 998244353LL;

constexpr f64 EPS = 1e-12;

constexpr f64 PI = 3.14159265358979323846;

#define M5 100007
#define M9 1000000000

#define F first
#define S second

// util {{{
#define FOR(i, start, end) for (i64 i = (start), CPP_CAT(i, xxxx_end) = (end); i < CPP_CAT(i, xxxx_end); ++i)
#define REP(i, n) FOR(i, 0, n)

#define all(x) (x).begin(), (x).end()
#define ll long long int
#define VI vector<ll>
#define VVI vector<VI>

#define ISD true
#define debug(x) \
    if (ISD)     \
    cout << #x << ": " << x << endl

template <typename T, typename U, typename Comp = less<>>
bool chmax(T &xmax, const U &x, Comp comp = {})
{
    if (comp(xmax, x))
    {
        xmax = x;
        return true;
    }
    return false;
}

template <typename T, typename U, typename Comp = less<>>
bool chmin(T &xmin, const U &x, Comp comp = {})
{
    if (comp(x, xmin))
    {
        xmin = x;
        return true;
    }
    return false;
}

struct UnionFind
{
    vector<int> par, rank;
    UnionFind(int n) : par(n), rank(n, 1)
    {
        for (int i = 0; i < n; i++)
            par[i] = i;
    }
    int find(int x)
    {
        if (par[x] == x)
            return x;
        return par[x] = find(par[x]);
    }
    void unite(int x, int y)
    {
        x = find(x);
        y = find(y);
        if (x == y)
            return;
        if (rank[x] < rank[y])
            swap(x, y);
        par[y] = x;
        if (rank[x] == rank[y])
            rank[x]++;
    }
    bool same(int x, int y)
    {
        return find(x) == find(y);
    }
};

int main()
{
    ll N, M;
    cin >> N >> M;
    vector<ll> A(M), B(M), C(M);
    REP(i, M)
    {
        cin >> A[i] >> B[i] >> C[i];
        A[i]--;
        B[i]--;
    }

    VI v(M);
    REP(i, M)
    v[i] = i;
    auto comp = [&](int a, int b)
    {
        return C[a] > C[b];
    };
    sort(all(v), comp);

    UnionFind uf(N);
    ll ans = 0;
    for (auto i : v)
    {
        if (!uf.same(A[i], B[i]))
        {
            uf.unite(A[i], B[i]);
            ans += C[i];
        }
    }
    cout << ans * 2 << endl;
}