/*************************************************************************

> File Name: 1231.cpp

> Author: dulun

> Mail: dulun@xiyoulinux.org

> Created Time: 2016年02月29日 星期一 14时08分49秒

************************************************************************/

#include<iostream>

#include<stdio.h>

#include<stdlib.h>

#include<algorithm>

using namespace std;

struct computer

{

int a,b,c;

};

computer com[100086];

int p[100086];

int m, n;

int find(int a){return p[a] == a ? a : p[a] = find(p[a]);}

int cmp(computer a, computer b){return a.c < b.c;}

int kruscal()

{

long long sum = 0;

int ans = 0;

for(int i = 0; i < m && ans < n; i++)

{

int x = find(com[i].a);

int y = find(com[i].b);

if( x != y )

{

sum += com[i].c;

p[x] = y;

ans++;

}

}

cout<<sum<<endl;

return 0;

}

int main()

{

cin>>n>>m;

for(int i = 0; i < n; i++)

{

p[i] = i;

}

for(int i = 0; i < m ; i++)

{

cin>>com[i].a;

cin>>com[i].b;

cin>>com[i].c;

}

sort(com, com + m, cmp);

kruscal();

return 0;

}