#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
const int maxn=1000+10;
const int maxm=20000+10;
 
struct Edge
{
    int u,v,dist;
    Edge(){}
    Edge(int u,int v,int d):u(u),v(v),dist(d){}
    bool operator<(const Edge &rhs)const
    {
        return dist >rhs.dist;//按邊長從大到小排序
    }
};
 
struct Kruskal
{
    int n,m;
    Edge edges[maxm];
    int fa[maxn];
    int findset(int x){ return fa[x]==-1?x: fa[x]=findset(fa[x]); }
 
    void init(int n)
    {
        this->n=n;
        m=0;
        memset(fa,-1,sizeof(fa));
    }
 
    void AddEdge(int u,int v,int dist)
    {
        edges[m++]=Edge(u,v,dist);
    }
 
    int kruskal()
    {
        int sum=0,cnt=0;
        sort(edges,edges+m);
 
        for(int i=0;i<m;i++)
        {
            int u=edges[i].u, v=edges[i].v;
            if(findset(u) != findset(v))
            {
                fa[findset(u)] = findset(v);
                sum += edges[i].dist;
                if(++cnt>=n-1) return sum;
            }
        }
        return -1;//圖不連通
    }
}KK;
 
int main()
{
    int n,m;
    scanf("%d%d",&n,&m);
    KK.init(n);
    while(m--)
    {
        int u,v,d;
        scanf("%d%d%d",&u,&v,&d);
        KK.AddEdge(u,v,d);
    }
    printf("%d\n",KK.kruskal());
    return 0;
}