#include<iostream>

#include<cstring>

#include<cstdio>

#include<algorithm>

#include<vector>

#include<queue>

using namespace std;

struct node

{

    int pos,cost;

    node(int a,int b):pos(a),cost(b){};

    friend bool operator <(node x,node y)

    {

        return x.cost > y.cost;

    }

};

struct edge

{

    int to,cost;

    edge(int a,int b):to(a),cost(b){};

};

vector<edge> v[];

bool vis[] = {};

int dis[],cost[],n,m;

void dij()

{

    memset(dis,0x3f,sizeof(dis));

    memset(cost,0x3f,sizeof(cost));

    dis[] = ;

    cost[] = ;

    priority_queue<node> q;

    q.push(node(,));

    while(!q.empty())

    {

        int now = q.top().pos;

        if(vis[now])    continue;

        vis[now] = ;

        for(int i = ;i < v[now].size();i++)

        {

            int to = v[now][i].to,c = v[now][i].cost;

            if(vis[to]) continue;

            if(dis[to] > dis[now]+c)

            {

                dis[to] = dis[now]+c;

                cost[to] = c;

                q.push(node(to,dis[to]));

            }

            else if(dis[to] == dis[now]+c)    cost[to] = min(cost[to],c);

        }

    }

}

int main()

{

    scanf("%d%d",&n,&m);

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

    {

        int a,b,c;

        scanf("%d%d%d",&a,&b,&c);

        v[a].push_back(edge(b,c));

        v[b].push_back(edge(a,c));

    }

    dij();

    int ans = ;

    for(int i = ;i <= n;i++)   ans += cost[i];

    printf("%d\n",ans);

    return ;

}