#include <stdio.h>
#include <algorithm>

struct edge
{
	int from, to, weight;
};

bool operator<(const edge& x, const edge& y)
{
	return x.weight < y.weight;
}

int *parent_of;

int get_parent(int node)
{
	if (parent_of[node] == 0)
		return node;

	// Change the parent of all intermediate nodes for faster subsequent searches
	return parent_of[node] = get_parent(parent_of[node]);
}

int main()
{
	int n, m;

	scanf("%d %d", &n, &m);

	parent_of = new int[n + 1]{};	// Initialize with zeroes
	edge *arr = new edge[m];

	long long int result = 0;

	for (int i = 0; i != m; ++i)
	{
		scanf("%d %d %d", &arr[i].from, &arr[i].to, &arr[i].weight);
		result += arr[i].weight;
	}

	std::sort(arr, arr + m);

	int edge_count = 1;
	int idx = 0;
	int p1, p2;
	while (edge_count < n && idx != m)
	{
		p1 = get_parent(arr[idx].from);
		p2 = get_parent(arr[idx].to);
		if (p1 != p2)	// Edge doesn't close a cycle, so the pick it
		{
			parent_of[p1] = p2;
			result -= arr[idx].weight;
			++edge_count;
		}
		++idx;
	}

	if (edge_count == n)
		printf("%lld\n", result);
	else
		printf("-1\n");
}