//prim算法
#include<cstdio>

#include<cmath>

#include<cstring>

#include<iostream>

#include<cstdlib>

#include<algorithm>

#include<string>

#include<stack>

#include<queue>

#include<map>

#define MAX 510

const int INF=1000000000;

using namespace std;

//顶点到集合s的最短距离

int d[MAX],G[MAX][MAX];

int n,m;

bool isVisit[MAX]={false};

//返回最小生成树的边权之和

int prim(){

    fill(d,d+MAX,INF);

    d[0]=0;

    int ans=0;

    for(int i=0;i<n;i++){

        int u=-1,MIN=INF;

        for(int j=0;j<n;j++){

            if(isVisit[j]==false&&d[j]<MIN){

                u=j;

                MIN=d[j];

            }

        }

        if(u==-1) return -1;

        isVisit[u]=true;

        ans+=d[u];

        for(int v=0;v<n;v++){

            if(isVisit[v]==false&&G[u][v]!=INF&&G[u][v]<d[v])

                d[v]=G[u][v];

        }

    }

    return ans;

}

int main(){

    int u,v,w;

    //顶点个数，边数

    scanf("%d%d",&n,&m);

    //初始化图

    fill(G[0],G[0]+MAX*MAX,INF);

    for(int i=0;i<m;i++){

        scanf("%d%d%d",&u,&v,&w);

        G[u][v]=G[v][u]=w;

    }

    int ans=prim();

    printf("%d\n",ans);

    return 0;

}

#include<cstdio>

#include<cmath>

#include<cstring>

#include<iostream>

#include<cstdlib>

#include<algorithm>

#include<string>

#include<stack>

#include<queue>

#include<map>

const int MAX=;

const int MAXE=;

const int INF=;

using namespace std;

//顶点到集合s的最短距离

int d[MAX],father[MAX];

int n,m;

bool isVisit[MAX]={false};

struct edge{

    int node1,node2;

    int weight;

}E[MAXE];

bool cmp(edge e1,edge e2){

    return e1.weight<e2.weight;

}

int findFather(int x){

    int a=x;

    while(x!=father[x]){

        x=father[x];

    }

    while(a!=father[a]){

        int temp=a;

        a=father[a];

        father[temp]=x;

    }

    return x;

}

int kruskal(){

    int ans=,num_edge=;

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

        father[i]=i;

    sort(E,E+m,cmp);

    for(int i=;i<m;i++){

        int f1=findFather(E[i].node1);

        int f2=findFather(E[i].node2);

        if(f1!=f2){

            father[f1]=f2;

            ans+=E[i].weight;

            num_edge++;

            //边数等于顶点数-1结束

            if(num_edge==n-) break;

        }

    }

    if(num_edge!=n-) return -;

    else return ans;

}

int main(){

    //顶点个数，边数

    scanf("%d%d",&n,&m);

    for(int i=;i<m;i++){

        scanf("%d%d%d",&E[i].node1,&E[i].node2,&E[i].weight);

    }

    int ans=kruskal();

    printf("%d\n",ans);

    return ;

}