/**

* Author: Dabananda Mitra

* Email: imdmitra@gmail.com

* GitHub: https://github.com/dabananda

* Created: 2024-09-27 19:19:28

* Problem Link: https://www.hackerrank.com/contests/assignment-02-a-introduction-to-algorithms-a-batch-05/challenges/building-3-1

*

*/

#include <bits/stdc++.h>

using namespace std;

#define ll long long

#define pi pair<int, int>

#define pb push_back

#define nl "\n"

const int N = 1e5 + 5;

int leader[N];

int groupSize[N];

class Edge {

public:

int u, v, w;

Edge(int u, int v, int w) {

this->u = u;

this->v = v;

this->w = w;

}

};

void dsuInit(int n) {

for (int i = 1; i <= n; i++) {

leader[i] = -1;

groupSize[i] = 1;

}

}

int getLeader(int node) {

if (leader[node] == -1) {

return node;

}

int l = getLeader(leader[node]);

leader[node] = l;

return l;

}

void makeUnion(int x, int y) {

int a = getLeader(x);

int b = getLeader(y);

if (groupSize[a] > groupSize[b]) {

leader[b] = a;

groupSize[a] += groupSize[b];

} else {

leader[a] = b;

groupSize[b] += groupSize[a];

}

}

bool comp(Edge a, Edge b) {

return a.w < b.w;

}

void solution() {

int n, e;

cin >> n >> e;

vector<Edge> edgeList;

while (e--) {

int u, v, w;

cin >> u >> v >> w;

edgeList.push_back(Edge(u, v, w));

}

sort(edgeList.begin(), edgeList.end(), comp);

long long int cost = 0;

dsuInit(n);

for (Edge ed : edgeList) {

int a = getLeader(ed.u);

int b = getLeader(ed.v);

if (a != b) {

makeUnion(a, b);

cost += ed.w;

}

}

int mainLeader = getLeader(1);

int flag = true;

for (int i = 2; i <= n; i++) {

if (getLeader(i) != mainLeader) {

flag = false;

break;

}

}

if (flag) {

cout << cost << endl;

} else {

cout << -1 << endl;

}

}

int main() {

ios::sync_with_stdio(0);

cin.tie(0);

cout.tie(0);

solution();

return 0;

}