#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int fa[1001];
int n,m,ans,num;
struct cow
{
    int bb,son,money;
};
cow tree[20001];
int find(int x)
{
    if(fa[x]!=x)
    fa[x]=find(fa[x]);
    return fa[x];
}
void add(int x,int y)
{
    fa[fa[x]]=fa[y];
}
bool cmp(cow x,cow y)
{
    return x.money>y.money;
}
int main()
{
    cin>>n>>m;
    for(int i=1;i<=n;i++)
    fa[i]=i;
    for(int i=1;i<=m;i++)
    {
        cin>>tree[i].bb>>tree[i].son>>tree[i].money;
    }
    sort(tree+1,tree+1+m,cmp); 
    for(int i=1;i<=n;i++)
    {
        if(find(tree[i].bb)!=find(tree[i].son))
        {
            add(tree[i].bb,tree[i].son);
            ans=ans+tree[i].money;
            num++;
        }
    }
    if(num==n-1)
        {
            cout<<ans;
            return 0;
        }
        else
        {
            cout<<-1;
            return 0;
        }
}