a129

#include"./template/headers.hpp"

//#define MULTI_TASKCASE
using namespace abb;
using namespace output;
using namespace rit;
using namespace wit;

inline void init() {

}

struct edge {
    int b, w;
    edge(int x, int y): b(x), w(y) {}
};
bool operator<(edge a, edge b) {return a.w > b.w;}

inline void solve() {
    int n, m;
    while (cin >> n >> m) {
        V<V<edge>> v(n);
        for (int i = 0; i != m; i++) {
            static int a, b, w;
            cin >> a >> b >> w;
            v[a].emplace_back(b, w);
            v[b].emplace_back(a, w);
        }
        V<bool> vis(n, false);
        V<ll> d(n, 1e15);
        PQ<edge> pq; pq.emplace(0, d[0] = 0);
        for (int i = 0; i < n; i++) {
            static int a; a = ~0u;
            while (pq.size() && vis[a = pq.top().b]) pq.pop();
            if (!~a) break;
            vis[a] = true;
            for (const auto& i : v[a])
                if (!vis[i.b] && i.w < d[i.b])
                    pq.emplace(i.b, d[i.b] = i.w);
        }
        if (find(d.begin(), d.end(), 1e15) != d.end())
            cout << -1 << endl;
        else
            cout << accumulate(d.begin(), d.end(), 0LL) << endl;
    }
}

main() {
    ios::sync_with_stdio(false);
    init();
    int t = 1;
#ifdef MULTI_TASKCASE
    cin >> t; cin.ignore();
#endif
    while (t--) solve();
    return 0;
}