import java.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;

public class Solution {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int n = scanner.nextInt();
        int m = scanner.nextInt();

        int[][] edges = new int[m][3];
        for (int i = 0; i < m; i++) {
            edges[i][0] = scanner.nextInt();
            edges[i][1] = scanner.nextInt();
            edges[i][2] = scanner.nextInt();
        }

        scanner.close();

        Solution solution = new Solution();

        System.out.println(solution.find(n, m, edges));
    }
    public int find(int n, int m, int[][] edges) {
        // Sort edges by decreasing order of reward
        Arrays.sort(edges, Comparator.comparingInt(a -> a[2]));

        // Initialize disjoint-set data structure
        int[] parent = new int[n + 1];
        for (int i = 1; i <= n; i++) {
            parent[i] = i;
        }

        int totalReward = 0;
        for (int[] edge : edges) {
            int parentA = findParent(edge[0], parent);
            int parentB = findParent(edge[1], parent);
            if (parentA != parentB || edge[2]<=0) {
                parent[parentB] = parentA;
            }
            else
                totalReward+=edge[2];
        }

        return totalReward;
    }

    private int findParent(int node, int[] parent) {
        if (parent[node] != node) {
            parent[node] = findParent(parent[node], parent);
        }
        return parent[node];
    }
}