#include <bits/stdc++.h>
#define startt ios_base::sync_with_stdio(false);cin.tie(0);
#pragma GCC target ("avx2")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
typedef unsigned long long ull;
typedef long long  ll;
using namespace std;
#define FOR(n) for(int i=0;i<n;i++)
#define vt vector
#define vint vector<int>
#define all(v) v.begin(), v.end()
#define MOD 1000000007
#define MOD2 998244353
#define MX 1000000000
#define nax 100005
#define MXL 1000000000000000000
#define PI 3.14159265
#define pb push_back
#define pf push_front
#define sc second
#define fr first
#define int ll
#define endl '\n'
#define ld long double

int nodes, edges;

const int NMAX = 2e5+5;

int pr[NMAX], sz[NMAX];

void initializedsu(int n)
{
	for(int i = 1; i <= n; i++)
	{
		pr[i] = i;
		sz[i] = 1;
	}
}

int find(int x)
{
	int parent;
	if(x == pr[x])
	{
		return x;
	}
	parent = find(pr[x]);
	pr[x] = parent;
	return parent;
}

void unite(int x, int y)
{
	int leaderx = find(x);
	int leadery = find(y);
	if(sz[leaderx] >= sz[leadery])
	{
		sz[leaderx]+=sz[leadery];
		pr[leadery] = leaderx;
	}
	else
	{
		sz[leadery]+=sz[leaderx];
		pr[leaderx] = leadery;
	}
}


vector<pair<int, int>> kruskal(pair<long long, pair<int, int> > p[])
{
	int x, y;
	vector<pair<int, int>> ans;
	long long cost, minimumCost = 0;
	for(int i = 0;i < edges;++i)
	{
		x = p[i].second.first;
		y = p[i].second.second;
		cost = p[i].first;
		if(find(x) != find(y))
		{
			ans.pb({x, y});
			minimumCost += cost;
			unite(x, y);
		}
	}
	cout << minimumCost << endl;
	return ans;
}

int32_t main(){
	startt;
	freopen("apm.in", "r", stdin);
	freopen("apm.out", "w", stdout);
	int x, y;
	long long weight;
	cin >> nodes >> edges;
	initializedsu(nodes);
	pair<int, pair<int, int>> p[nodes+1];
	for(int i = 0;i < edges;++i)
	{
		cin >> x >> y >> weight;
		p[i] = make_pair(weight, make_pair(x, y));
	}
	sort(p, p + edges);
	vector<pair<int, int>> a = kruskal(p);
	cout << a.size() << endl;
	for(auto p : a)
	{
		cout << p.fr << " " << p.sc << endl;
	}
}