#include <cstdio>
#include <climits>
#include <set>
#include <vector>
using namespace std;

struct Edge {
    int x; // from
    int y; // to
    int v; // length
    int d; // distance from root
    Edge(int x_, int y_, int v_, int d_) : x(x_), y(y_), v(v_), d(d_) {}
    bool operator<(const Edge &b) const {
        if(d < b.d) return true;
        else if(d == b.d && v < b.v) return true;
        return false;
    }
};

int main() {
    int N, M;
    scanf("%d%d", &N, &M);
    vector<vector<Edge> > graph(N+1, vector<Edge>());
    for(int m=0; m<M; m++) {
        int x, y, v;
        scanf("%d%d%d", &x, &y, &v);
        graph[x].push_back(Edge(x,y,v,0));
        graph[y].push_back(Edge(y,x,v,0));
    }
    
    vector<int> dist(N+1, INT_MAX);
    vector<bool> visited(N+1);
    
    multiset<Edge> s;
    s.insert(Edge(1,1,0,0));
    dist[1] = 0;
    
    int result = 0;    
    while(!s.empty()) {
        Edge e = *s.begin();
        //printf("E: %d %d %d %d\n", e.x, e.y, e.v, e.d);
        int from = e.y;
        s.erase(s.begin());
        if(visited[from]) continue;
        visited[from] = true;
        result += e.v;
        for(int i=0; i<graph[from].size(); i++) {
            int to = graph[from][i].y;
            int v = graph[from][i].v;
            if(dist[from] + v <= dist[to]) {
                dist[to] = dist[from] + v;
                s.insert(Edge(from, to, v, dist[to]));
            }
        }
    }
    printf("%d", result);
}