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

using ll = long long;
#define int ll
#define all(v) (v).begin(), (v).end()
#define pb push_back

void dbg_out() { cerr << endl; }
template<typename H, typename... T> 
void dbg_out(H h, T... t) { cerr << ' ' << h; dbg_out(t...); }
#define dbg(...) { cerr << #__VA_ARGS__ << ':'; dbg_out(__VA_ARGS__); }

struct edge{
	int u,v,w;
	int id;
	bool operator<(const edge &e) const{
		return w < e.w;
	}
};

void solve() {
	int n,m;
	cin >> n >> m;
	vector<int> esta(m);
	for(int i = 0; i < n-1; i++){
		esta[i] = 1;
	}
	vector<edge> e(m);
	for(int i = 0; i < m; i++){
		cin >> e[i].u >> e[i].v >> e[i].w;
		e[i].u--;
		e[i].v--;
		e[i].id = i;
	}
	sort(e.begin(), e.end());
	vector<pair<int,int>> ans;
	for(int k = 0; k < m; k++){
		if(!esta[e[k].id]) continue;
		vector<int> uf(n);
		vector<int> sz(n);
		for(int i = 0; i < n; i++){
			uf[i] = i;
			sz[i] = 1;
		}
		function<int(int)> find = [&](int x){ 
			return x == uf[x] ? x : uf[x]=find(uf[x]);
		};
		auto uni = [&](int a, int b){
			a = find(a);
			b = find(b);
			if(a == b) return 0;
			if(sz[a] > sz[b]) swap(a,b);
			sz[b] += sz[a];
			uf[a] = b;
			return 1;
		};
		for(int i = 0; i < m; i++){
			if(esta[e[i].id] && i != k) uni(e[i].u, e[i].v);
		}
		for(int i = 0; i < k; i++){
			if(esta[e[i].id]) continue;
			if(e[i].w == e[k].w) continue;
			int ret = uni(e[i].u, e[i].v);
			if(ret){
				ans.pb( {e[i].id, e[k].id});
				esta[e[i].id] = 1;
				esta[e[k].id] = 0;
				break;
			}
		}
	}
	cout << ans.size() << '\n';
	for(auto [a,b] : ans){
		cout << b+1 << ' ' << a+1 << '\n';
	}

}

signed main() {
    ios::sync_with_stdio(false); cin.tie(0);
    int t = 1;
    while(t--)
        solve();
}