import java.util.*;

public class _1647_1 {
    static int[] parents;
    static int[] rank;

    static int find(int x) {
        if(x != parents[x]) return parents[x] = find(parents[x]);
        return x;
    }

    static void union(int x, int y) {
        x = find(x);
        y = find(y);

        if(x==y) return;

        if(rank[x] < rank[y]) {
            int temp = x;
            x = y;
            y = temp;
        }

        if(rank[x] == rank[y]) rank[x]++;

        parents[y] = x;
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt(), M = sc.nextInt();

        if(N==2) {
            System.out.println(0);
            return;
        }

        ArrayList<int[]> edges = new ArrayList<>();

        for(int i=0; i<M; i++) {
            int A = sc.nextInt(), B = sc.nextInt(), C = sc.nextInt();
            int[] edge = {A, B, C};
            edges.add(edge);
        }
        sc.close();

        edges.sort((a,b) -> a[2] - b[2]);

        parents = new int[N+1];
        for(int i=1; i<=N; i++) parents[i] = i;
        rank = new int[N+1];

        int cnt = 0, ans = 0;
        
        for (int[] edge : edges) {
            int a = edge[0], b = edge[1], c = edge[2];

            if(find(a) == find(b)) continue;

            union(a, b);
            cnt += 1;
            ans += c;
            if(cnt == N-2) break;
        }

        System.out.println(ans);
    }
}