import java util ArrayList import java util Arrays import java util Sc

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Scanner;
import java.lang.Math;

class point {
    int index=-2;
    int key;
    int value;
    int cap;
    ArrayList<Integer> list = new ArrayList<Integer>(); //хранит массив roads,связанных с этой вершиной
}

class rib {
    int from;
    int to;
    int distance;
}

class PriorityQueue{
    int count;
    point[] heap;
    PriorityQueue(int n){
        int i;
        this.heap = new point[n];
        for(i = 0; i < n; i++){
            this.heap[i] = new point();
        }
        this.count = 0;
    }
    public void insert(point u){
        int i = this.count++;
        point temp;
        this.heap[i] = u;
        while (i > 0 && this.heap[(i-1)/2].key > this.heap[i].key){
            temp = this.heap[(i-1)/2];
            this.heap[(i-1)/2] = this.heap[i];
            this.heap[i] = temp;
            this.heap[i].index=i;
            i = (i-1)/2;
        }
        this.heap[i].index=i;
    }
    public point ExtractMin(){
        point temp;
        temp = this.heap[0];
        this.count--;
        if(this.count > 0){
            this.heap[0] = this.heap[this.count];
            this.heap[0].index=0;
            heapify(this.heap, 0);
        }
        return temp;
    }
    public void heapify(point[] heap, int i){
        int l, r, j;
        point temp;
        for(;;){
            l = 2*i+1;
            r = l+1;
            j = i;
            if(l < this.count && (heap[l].key < heap[j].key)) j = l;
            if(r < this.count && (heap[r].key < heap[j].key)) j = r;
            if(i == j) break;
            temp = heap[i];
            heap[i] = heap[j];
            heap[j] = temp;
            this.heap[i].index=i;
            this.heap[j].index=j;
            i = j;
        }
    }
    public void increaseKey(point x, int y){
        int i = x.index;
        point temp;
        x.key=y;
        while(i > 0 && this.heap[(i-1)/2].key > y){
            temp = this.heap[(i-1)/2];
            this.heap[(i-1)/2] = this.heap[i];
            this.heap[i] = temp;
            this.heap[i].index=i;
            i = (i-1)/2;
        }
        x.index=i;
    }
}


public class Prim {
    public static void main(String[] arg) {
        Scanner sc = new Scanner(System.in);
        int i=0,j=0,n=sc.nextInt(),m=sc.nextInt(),first,second,third,distance=0;
        point [] graph=new point[n];
        rib [] roads=new rib[m];
        PriorityQueue q = new PriorityQueue(m);
        for(i=0;i<n;i++)
        {
            graph[i]=new point();
        }

        for(i=0;i<m;i++)
        {
            roads[i]=new rib();
            roads[i].from=sc.nextInt();
            roads[i].to=sc.nextInt();
            roads[i].distance=sc.nextInt();
            graph[roads[i].from].cap++;
            graph[roads[i].from].list.add(i);
            graph[roads[i].to].cap++;
            graph[roads[i].to].list.add(i);
        }

        point temp1;
        point temp2;
        //добавляем нулевую вершину по алгоритму Прима
        for(i=0;i<graph[0].list.size();i++)
        {
            graph[0].key=0;
            graph[0].index=-2;
            q.insert(graph[0]);
        }

        int count=0;
        while(q.count!=0)
        {
            temp1=q.ExtractMin();
            distance+=temp1.key;
            count++;
            temp1.index=-1;
            for(i=0;i<temp1.cap;i++)
            {
                //обозначение второй вершины
                if(graph[roads[temp1.list.get(i)].to].index!=-1)
                    temp2=graph[roads[temp1.list.get(i)].to];
                else
                    temp2=graph[roads[temp1.list.get(i)].from];
                //обновляем расстояния после соединения точки и позицию точек в пирамиде
                if(temp2.index==-2)
                {
                    temp2.key=roads[temp1.list.get(i)].distance;
                    q.insert(temp2);
                }
                else if(temp2.key>roads[temp1.list.get(i)].distance)
                {
                    //temp2.key=roads[temp1.list.get(i)].distance;
                    q.increaseKey(temp2,roads[temp1.list.get(i)].distance);
                }

            }
        }
        System.out.println(distance);
    }
}