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 a, b; ll v;
};
bool operator<(edge a, edge b) {
    return a.v < b.v;
};

inline void solve() {
    int n, m;
    while (cin >> n >> m) {
        V<edge> v(m);
        for (auto& i : v)
            cin >> i.a >> i.b >> i.v;
        sort(v.begin(), v.end());
        V<int> d(n);
        iota(d.begin(), d.end(), 0);
        F<int(int)> find = [&](int x) {
            return x == d[x] ? x : (d[x] = find(d[x]));
        };
        auto merge = [&](int a, int b) {
            d[find(a)] = find(b);
        };
        ll ans = 0;
        for (auto& i : v)
            if (find(i.a) != find(i.b))
                ans += i.v, merge(i.a, i.b);
        for (int i = 1; i < n; i++)
            if (find(0) != find(i))
                goto no_result;
        cout << ans << endl;
        continue;
no_result :
        cout << -1 << endl;
    }
}

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