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

#define rep(i, l, r) for (int i = (int)(l); i<(int)(r); i++)
#define ll long long

//MST
//{辺長, u, v} の vector<tuple<ll, int, int>> を渡す
//m = false : 最小全域木、m = true : 最大全域木
long long MST(vector<tuple<long long, int, int>> E, int N, bool m) {
    int M = (int)E.size();
    if (!m) sort(E.begin(), E.end());
    else sort(E.begin(), E.end(), greater<tuple<long long, int, int>>());
    atcoder::dsu d(N);
    long long ret = 0;
    for (int i=0; i<M; i++) {
        if (!d.same(get<1>(E[i]), get<2>(E[i]))) {
            ret+=(long long) get<0>(E[i]);
            d.merge(get<1>(E[i]), get<2>(E[i]));
        }
    }
    return ret;
}

int main() {
    int N, M; cin >> N >> M;
    vector<tuple<ll, int, int>> E(M);
    rep(i, 0, M) {
        int a, b; ll c; cin >> a >> b >> c;
        E[i] = {c, a-1, b-1};
    }
    cout << MST(E, N, true)*2 << endl;
}