#include <iostream>

 using namespace std;

 int N, M;

 int** G;

 void buildGraph();

 void deleteGraph();

 int prim();

 int findMinDist(int dist[]);

 int main()

 {

     cin >> N >> M;

     buildGraph();

     cout << prim();

     deleteGraph();

     return ;

 }

 void buildGraph()

 {

     int i, j;

     G = new int*[N];

     for (i = ; i < N; i++)

     {

         G[i] = new int[N];

         for (j = ; j < N; j++)

             G[i][j] = INT_MAX;

     }    

     int v, w, d;

     for (i = ; i < M; i++)

     {

         cin >> v >> w >> d;

         v--; w--;//输入从1计数

         G[v][w] = d;

         G[w][v] = d;

     }

 }

 void deleteGraph()

 {

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

         delete[] G[i];

     delete[] G;

 }

 int findMinDist(int dist[])

 { /*返回未收录进MST的顶点中dist最小的顶点*/

     int minV, v;

     int minDist = INT_MAX;

     for (v = ; v < N; v++)

     {

         if (dist[v] !=  && dist[v] < minDist)

         {

             minDist = dist[v];

             minV = v;

         }

     }

     if (minDist < INT_MAX)

         return minV;

     return -;

 }

 int prim()

 { /*返回最小生成树的权重*/

     int v, w, vCount = ;

     int totalWeight = ;

     int* dist = new int[N];

     /*初始化，初始点下标为0*/

     for (v = ; v < N; v++)

         dist[v] = G[][v];

     /*将0收进最小生成树MST*/

     dist[] = ;

     vCount++;

     while (true)

     {

         v = findMinDist(dist);

         if (v == -)

             break;

         totalWeight += dist[v];

         dist[v] = ; //收录v

         vCount++;

         for (w = ; w < N; w++)

         {

             /*如果w没有被收录*/

             if (dist[w] !=  && G[v][w] < dist[w])

             {

                 dist[w] = G[v][w];

             }

         }

     }

     delete[] dist;

     if (vCount < N)

         return -;

     return totalWeight;

 }