#include<iostream>

#include<cmath>

#include<algorithm>

using namespace std;

const int maxn=;

struct edge{int x,y,z;}a[maxn];

int n,m,prt[maxn],ans=,bj;

bool cmp(const edge&x,const edge&y){return x.z<y.z;}

int father(int x)

{

    if(prt[x]==x) return x;

    prt[x]=father(prt[x]);

    return prt[x];

}

void kru()

{

    int f1,f2,k,i;

    k=;

    for(int i=;i<=n;i++) prt[i]=i;

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

    {

        f1=father(a[i].x);

        f2=father(a[i].y);

        if(f1!=f2)

        {

            ans=ans+a[i].z;

            prt[f1]=f2;

            k++;

            if(k==n-) break;

        }

    }

    if(k<n-)

    {

        cout<<"-1"<<endl;

        bj=;

        return;

    }

}

int main()

{

    cin>>n>>m;

    ans=-;

    bj=;

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

      cin>>a[i].x>>a[i].y>>a[i].z;

    sort(a+,a+m+,cmp);

    kru();

    if(bj) cout<<ans<<endl;

    return ;

}