#include<bits/stdc++.h>
#define int long long

using namespace std;

const int MAXN = 2001;

#define rep(i, from, to) for (int i = from; i < (to); ++i)
#define all(x) x.begin(), x.end()
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;

struct UF {
	vi e;
	UF(int n) : e(n, -1) {}
	bool sameSet(int a, int b) { return find(a) == find(b); }
	int size(int x) { return -e[find(x)]; }
	int find(int x) { return e[x] < 0 ? x : e[x] = find(e[x]); }
	bool join(int a, int b) {
		a = find(a), b = find(b);
		if (a == b) return false;
		if (e[a] > e[b]) swap(a, b);
		e[a] += e[b]; e[b] = a;
		return true;
	}
};

bool flag[3001];
int n, m;

void initMST(vector<tuple<int, int, int, int>> ed) {
	UF dsu(n);
	sort(ed.begin(), ed.end());

	for (auto &[w, id, u, v]: ed) {
		if (dsu.join(u, v)) {
			flag[id] = 1;
		}
	}
}

signed main(){
	ios::sync_with_stdio(0); cin.tie(0);
	// freopen("input.txt","r",stdin);
	// freopen("output.txt","w",stdout);

	cin >> n >> m;

	vector<tuple<int, int, int, int>> ed;

	for (int i = 0 ; i < m ; i++) {
		int u, v, w;

		cin >> u >> v >> w;
		u -= 1, v -= 1;

		ed.push_back({w, i, u, v});
	}

	initMST(ed);

	vector<pair<int, int>> res;

	vector<bool> flag2(m);

	for (int i = 0 ; i < n - 1 ; i++) {
		flag2[i] = 1;
	}

	for (int i = 0 ; i < n-1 ; i++) {
		if (!flag[i]) {
			UF dsu(n);

			for (int j = 0 ; j < m ; j++) {
				auto &[w, id, u, v] = ed[j];
				if (j != i && flag2[j]) {
					dsu.join(u, v);
				}
			}

			for (int j = n-1 ; j < m ; j++) {
				auto &[w, id, u, v] = ed[j];
				if (flag[j] && dsu.join(u, v)) {
					res.push_back({i, j});
					flag[j] = 0;
					flag[i] = 1;
					flag2[i] = 0;
					flag2[j] = 1;
					break;
				}
			}
		}
	}

	cout << res.size() << "\n";

	for (auto &[u, v]: res) {
		cout << u + 1 << " " << v + 1 << "\n";
	}
	return 0;
}