#include <stdio.h>
#include <bits/stdc++.h>
//%lld
typedef long long ll;
#define si(a) scanf("%d", &a)
#define sii(a, b) scanf("%d%d", &a, &b)
#define pi(a) printf("%d\n", a)

using namespace std;
struct par{
    int v;
    int t;
};

vector<par>grafo[100005];
bool marcado[100005];
ll custo[100005];
int pai[100000000];
int main(){
    priority_queue<pair<int, int>, vector<pair<int, int> >, greater<pair<int, int> > > fila;
    int n, m, c, f, t, a, b;
    int g = 1;
    while(g--){
        memset(marcado, false, sizeof(marcado));
        memset(grafo, 0, sizeof(grafo));
        fill(custo, custo+100005, 1000000000);
        scanf("%d%d", &n, &m);
        f = 0;
        for(int i = 0;i<m;i++){
            sii(a, b);
            int peso;
            si(peso);
            par aux;
            if(a>f)f = a;
            aux.v= b;
            aux.t = peso;
            grafo[a].push_back(aux);
            aux.v= a;
            aux.t = peso;
            grafo[b].push_back(aux);
        }
        fila.push(pair<int, int>(0, 1));//pair<indice, custo>
        marcado[1] = true;
        custo[1] = 0;
        pai[1] = 1;
        int sai = 0;
        while(!fila.empty()){
            pair<int, int> f = fila.top();
            int auxx = f.first;
            int aux = f.second;
            fila.pop();
            marcado[aux] = true;
            for(int i = 0;i<(grafo[aux].size());i++){
                if(!marcado[grafo[aux][i].v]){
                        if(custo[grafo[aux][i].v]>(grafo[aux][i].t)+auxx){
                           custo[grafo[aux][i].v]=(grafo[aux][i].t)+auxx;
                           fila.push(pair<int, int>(custo[grafo[aux][i].v],grafo[aux][i].v));
                           pai[grafo[aux][i].v] = aux;
                        }
                }
            }
        }
        for(int i = 2;i<=f;i++){
            sai+=custo[i]-custo[pai[i]];
        }
        cout<<sai<<endl;;
    }
}