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

struct Edge {
    int u, v;
    long long w;
    bool operator<(const Edge& other) const {
        return w < other.w;
    }
};

struct DSU {
    vector<int> parent;
    DSU(int n) {
        parent.resize(n + 1);
        for (int i = 1; i <= n; i++) parent[i] = i;
    }
    int find(int v) {
        if (v == parent[v]) return v;
        return parent[v] = find(parent[v]);
    }
    bool unite(int a, int b) {
        a = find(a); b = find(b);
        if (a == b) return false;
        parent[b] = a;
        return true;
    }
};

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int n, m;
    if (!(cin >> n >> m)) return 0;
    vector<Edge> edges(m);
    long long total_weight = 0;
    for (int i = 0; i < m; i++) {
        cin >> edges[i].u >> edges[i].v >> edges[i].w;
        total_weight += edges[i].w;
    }
    sort(edges.begin(), edges.end());
    DSU dsu(n);
    long long mst_weight = 0;
    int edges_used = 0;
    for (auto& e : edges) {
        if (dsu.unite(e.u, e.v)) {
            mst_weight += e.w;
            edges_used++;
            if (edges_used == n - 1) break;
        }
    }
    if (edges_used == n - 1 || (n == 1 && edges_used == 0)) {
        cout << total_weight - mst_weight << "\n";
    } else {
        cout << -1 << "\n";
    }
    return 0;
}