#include <bits/stdc++.h>

using namespace std;

#ifdef LOCAL
#include "../debug.h"
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif

#define pb    push_back

const int N = 2010;

vector <vector<int>> g[N];

int main(){
	ios_base::sync_with_stdio(0); cin.tie(0);
	int n, m; cin >> n >> m;
	vector <pair<pair<int,int>,pair<int,int>>> edges;

	vector <int> visi(m,0);
	
	for (int i = 0; i < m; ++i) { 
		int u, v, w; 
		cin >> u >> v >> w;
		u--;v--;
	  g[u].pb({v,w,i});
		g[v].pb({u, w, i}); 
		if (i + 1 >= n) visi[i] = 1;
		edges.push_back({{w, i}, {u, v}});
	}
	sort (edges.begin(), edges.end());

	int ans = 0;
	vector <pair<int,int>> ops;
	for (auto &e : edges) { 
		int w = e.first.first;
		int idx = e.first.second;
		int u = e.second.first;
		int v = e.second.second;

		queue <pair<int,pair<int,int>>> q;
		q.push({u, {0, -1}});
		vector <int> pss(n);
		pss[u] = 1;
		while (q.size()) { 
			pair<int,pair<int,int>> tp = q.front();
			q.pop();
			if (tp.first == v) { 
				if (tp.second.first > w) { 
					visi[tp.second.second] = 1;
					visi[idx] = 0;
					ops.pb({tp.second.second + 1, idx + 1});
					ans++;
				}
				break;
			}
			for (auto &v : g[tp.first]) { 
				if (visi[v[2]] || pss[v[0]]) continue;
				if (tp.second.first > v[1]) q.push({v[0], tp.second});
				else q.push({v[0], {v[1], v[2]}});
	      pss[v[0]] = 1;
			}
		}

	}
	cout << ans << '\n';
	for (auto &e : ops) cout << e.first << ' ' << e.second << '\n';
	return 0;
}