#include<iostream>
#include <fstream>
#include<algorithm>
#include <vector>

using namespace std;
ifstream fin("apm.in");
ofstream fout("apm.out");

const int maxn = 400100;

int GR[maxn], X[maxn], Y[maxn], C[maxn];
int N, M, ANS, IND[maxn];
vector<vector<int>> ARB(maxn, vector<int>());

int grupa(int i) {
	if (GR[i] == i) return i;
	GR[i] = grupa(GR[i]);
	return GR[i];
}

void reuniune(int i, int j) {
	GR[grupa(i)] = grupa(j);
}

bool cmpf(int i, int j) {
	return(C[i] < C[j]);
}

int main() {
	fin >> N >> M;
	for (int i = 1; i <= M; ++i) {
		fin >> X[i] >> Y[i] >> C[i];
		IND[i] = i;
	}
	for (int i = 1; i <= N; ++i) GR[i] = i;
	sort(IND + 1, IND + M + 1, cmpf);//sortam muchiile dupa cost

	for (int i = 1; i <= M; ++i) {

		if (grupa(X[IND[i]]) != grupa(Y[IND[i]])) {
			ANS += C[IND[i]];
			reuniune(X[IND[i]], Y[IND[i]]);
		}
	}
	cout << ANS << "\n";
	for (int i = 1; i <= N; ++i)
		ARB[GR[i]].push_back(i);

	for (int i = 1; i <= N; ++i) {
		for (int j = 0; j < ARB[i].size(); ++j)
			fout << ARB[i][j] << " ";
		fout << "\n";
	}

	return 0;
}