#include <iostream>
#include <cstdio>
#include <vector>
#include <set>
#include <utility>
#include <algorithm>
using namespace std;

vector<long long> parent;
vector<pair<long long, pair<long long, long long> > > graph;

long long find_parent(long long node) {
    if (node != parent[node])
        parent[node] = find_parent(parent[node]);
    return parent[node];
}

int main() {
    long long N, M;
    cin >> N >> M;
    for (int i = 0; i <= N; i++)
        parent.push_back(i);
    for (long long i = 0; i < M; i++) {
        long long from, to, cost;
        cin >> from >> to >> cost;
        pair<long long, long long> edge(from, to);
        graph.push_back(pair<long long, pair<long long, long long> >(-cost, edge));
    }
    set<long long> nodes_visited;
    int visited_count = 0;
    long long cost = 0;
    sort(graph.begin(), graph.end());
    for (long long i = 0; i < graph.size() && nodes_visited.size() != N; i++) {
        long long p1, p2;
        p1 = find_parent(graph[i].second.first);
        p2 = find_parent(graph[i].second.second);
        if (p1 != p2) {
            cost += graph[i].first;
            visited_count++;
            parent[p1] = parent[p2];
            //for (int i = 1; i < parent.size(); i++) cout << parent[i] << " "; cout << "\n";
        }
    }
    if (visited_count != N - 1) cout << "-1" << "\n";
    else cout << -cost << "\n";
}