#include <iostream>
#include <vector>
#include <algorithm>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using mint = modint998244353;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
using vmi = vector<mint>;
using vvmi = vector<vmi>;
using vvvmi = vector<vvmi>;
#define all(a) (a).begin(), (a).end()
#define rep2(i, m, n) for (int i = (m); i < (n); ++i)
#define rep(i, n) rep2(i, 0, n)
#define drep2(i, m, n) for (int i = (m)-1; i >= (n); --i)
#define drep(i, n) drep2(i, n, 0)
using p = pair<int, int>;

int main(){
    ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    int n, m; cin >> n >> m;
    vector<pair<ll, p>> vp(m);
    rep(i, m){
        int a, b; ll c; cin >> a >> b >> c;
        vp[i] = {c, {a-1, b-1}};
    }
    sort(all(vp), greater<pair<ll, p>>());
    dsu d(n);
    int itr = 0;
    ll ans = 0;
    while(d.size(0) < n){
        auto [a, b] = vp[itr];
        if(!d.same(b.first, b.second)){
            ans += a;
            d.merge(b.first, b.second);
        }

        itr++;
    }
    cout << 2*ans << endl;
    return 0;
}