#include <bits/stdc++.h>
using namespace std;

#define int long long

struct DSU {
	vector<int> P, S;
	DSU(int n) {
		P.resize(n+1);
		S.resize(n+1, 1);
		for (int i = 1; i <= n; i++) P[i] = i;
	}
	
	int find(int x) {
		if (x == P[x]) return x;
		return P[x] = find(P[x]);
	}
	
	bool merge(int a, int b) {
		a = find(a); b = find(b);
		if (a == b) return 0;
		if (S[a] < S[b]) swap(a, b);
		
		S[a] += S[b];
		P[b] = a;
		return 1;
	}
	
	int same(int a, int b) {
		return find(a) == find(b);
	}
};

pair<int, int> rep(int n, int m, vector<pair<int, int>> &e, vector<int> &cur, vector<int> &mst) {
	// choose an edge in MST
	int add_id;
	for (int i = 0; i < m; i++) {
		if (!cur[i] && mst[i]) {
			add_id = i; break;
		}
	}

	// connect that
	DSU d(n);
	d.merge(e[add_id].first, e[add_id].second);

	// now connect whatever
	int del_id;
	for (int i = 0; i < m; i++) {
		if (cur[i] && mst[i]) {
			d.merge(e[i].first, e[i].second);
		}
	}
	for (int i = 0; i < m; i++) {
		if (cur[i] && !mst[i]) {
			if (d.merge(e[i].first, e[i].second)) {
				continue;
			} else {
				del_id = i; break;
			}
		}
	}

	cur[add_id] = 1;
	cur[del_id] = 0;
	return {del_id, add_id};
}

signed main() {
	ios::sync_with_stdio(0); cin.tie(0);

	int n, m; cin >> n >> m;
	vector<tuple<int, int, int, int>> edges;
	vector<pair<int, int>> e;
	for (int i = 0; i < m; i++) {
		int u, v, w; cin >> u >> v >> w;
		edges.emplace_back(w, i, u, v);
		e.emplace_back(u, v);
	}
	sort(edges.begin(), edges.end());

	vector<int> cur(m), mst(m);
	for (int i = 0; i < n-1; i++) {
		cur[i] = 1;
	} 

	DSU d(n);
	for (auto [w, i, x, y]: edges) {
		if (d.merge(x, y)) {
			mst[i] = 1;
		}
	}

	vector<pair<int, int>> ans;
	while (cur != mst) {
		ans.push_back(rep(n, m, e, cur, mst));
	}

	cout << ans.size() << '\n';
	for (auto [x, y]: ans) {
		cout << x+1 << ' ' << y+1 << '\n';
	}

	return 0;
}