#include <cstdio>
#include <cstring>
#define INF 1000000	//无穷大
#define MAXN 21		//顶点个数最大值

int n, m;		//顶点个数、边数
int Edge[MAXN][MAXN];	//邻接矩阵
int lowcost[MAXN];
int nearvex[MAXN];

void prim( int u0 )	//从顶点u0出发执行普里姆算法
{
	int i, j;	//循环变量
	int sumweight = 0;	//生成树的权值
	for( i=1; i<=n; i++ )	//初始化lowcost数组和nearvex数组
	{
		lowcost[i] = Edge[u0][i];  nearvex[i] = u0;
	}
	nearvex[u0] = -1;
for( i=1; i<n; i++ )
	{
		int min = INF;
		int v = -1;
		for( j=1; j<=n; j++ ) //在lowcost数组(nearvex[ ]值为-1的元素)找最小值
		{
			if( nearvex[j]!=-1 && lowcost[j]<min )
			{ v = j; min = lowcost[j]; }
		}
		if( v!=-1 )	//v==-1，表示没找到权值最小的边
		{
			//printf( "%d %d %d\n", nearvex[v], v, lowcost[v] );
			nearvex[v] = -1;
			sumweight += lowcost[v];
			
			for( j=1; j<=n; j++ )
			{
				if( nearvex[j]!=-1 && Edge[v][j]<lowcost[j] )
				{
					lowcost[j] = Edge[v][j];
					nearvex[j] = v;
				}
			}
		}//end of if
	}//end of for
	printf("%d",sumweight);
}//end of prime
int main( )
{
	int i, j;	//循环变量
	int u, v, w;	//边的起点和终点及权值
	scanf( "%d%d", &n, &m );	//读入顶点个数n和边数m
	memset( Edge, 0, sizeof(Edge) );
	for( i=1; i<=m; i++ )
	{
		scanf( "%d%d%d", &u, &v, &w );	//读入边的起点和终点
		Edge[u][v] = Edge[v][u] = w;	//构造邻接矩阵
	}
	for( i=1; i<=n; i++ )	//对邻接矩阵中其他元素值进行赋值
	{
		for( j=1; j<=n; j++ )
		{
			if( i==j ) Edge[i][j] = 0;
			else if( Edge[i][j]==0 )  Edge[i][j] = INF;
		}
	}
	prim( 1 );	//从顶点1出发构造最小生成树
	return 0;
}