ll@n,@m,a[m],b[],w[],z=0;
rd((a,b,w)(m));
sortA(m,w,a,b);
unionFind u('m',n+1,1);
rep(i,m){
	if(u(a[i])!=u(b[i])){
		z+=w[i]*u.size(a[i])*u.size(b[i]);
		u(a[i],b[i]);
	}
}
wt(z);