#include<iostream>
#include<cstdio>
#include<cstring>
#include<vector>
#include<algorithm>
#include<cmath>
#include<queue>
#include<map>
#include<stack>
#include<set>
using namespace std;
typedef long long ll;
const int maxn=300010;

const int N=10010;
int n,m;
struct node{
	int v,val; 
	node(int vv,int vall){
		v=vv,val=vall;
	}
	friend bool operator<(const node &a,const node &b){
		return a.val > b.val;
	}
};
priority_queue<node> que;
struct edge{
	int to,val;   
	edge(int too,int vall){
		to=too,val=vall;
	}
};
vector<edge> vec[100010];
int dis[N];
int vis[N];
int f[N];
void dij(){
	int i;
	que.push(node(1,0));
	int v;
	for(i=1;i<=n;++i){
		dis[i]=0xfffffff;
		f[i]=0xfffffff;
	}
	dis[1]=0;
	f[1]=0;
	while(!que.empty()){
		v=que.top().v; que.pop();
		if(vis[v]) continue;
		vis[v]=true;
		for(i=0;i<vec[v].size();++i){
			if(!vis[vec[v][i].to]&&dis[vec[v][i].to]>=dis[v]+vec[v][i].val){
				dis[vec[v][i].to]=dis[v]+vec[v][i].val;
				f[vec[v][i].to]=min(f[vec[v][i].to],vec[v][i].val);
				que.push(node(vec[v][i].to,dis[vec[v][i].to]));
			}
		}

	}
}
int main(){
	scanf("%d%d",&n,&m);
	int i;
	int u,v,l;
	for(i=0;i<m;++i){
		scanf("%d%d%d",&u,&v,&l);
		vec[u].push_back(edge(v,l));  
		vec[v].push_back(edge(u,l));
	}
	dij();
	int ans=0;
	for(i=1;i<=n;++i){
		ans+=f[i];
	}
	cout<<ans<<endl;
    return 0;
}