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

using ll = long long;
//#define int ll
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
using pii = pair<int, int>;
using vi = vector<int>;
#define fi first
#define se second
#define pb push_back

struct Edge
{
    int w,i,u,v;
    auto operator<=>(const Edge&)const=default;
};

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;
    }
};

signed main() {
	cin.tie(0)->sync_with_stdio(0);
	cin.exceptions(cin.failbit);

    int n,m;
    cin>>n>>m;
    vector<Edge> edges;
    for(int i=1;i<=m;i++)
    {
        int u,v,w;
        cin>>u>>v>>w;
        edges.pb({w,i,u,v});
    }
    set<Edge> edges_before(edges.begin(),edges.begin()+n-1);
    sort(all(edges));
    UF dsu1(n+1),dsu2(n+1);
    set<Edge> edges_after;
    int k=0;
    for(auto edge:edges)
    {
        if(dsu1.join(edge.u,edge.v)) {
            edges_after.insert(edge);
            if(!edges_before.contains(edge))
                k++;
            else
                dsu2.join(edge.u,edge.v);
        }
    }
    cout<<k<<"\n";
    while(k--)
    {
        vi deg(n+1);
        for(auto edge:edges_before)
            if(!dsu2.sameSet(edge.u,edge.v))
                deg[dsu2.find(edge.u)]++,
                deg[dsu2.find(edge.v)]++;
        int leaf=find(all(deg),1)-deg.begin();
        assert(leaf!=n+1);
        for(auto edge:edges_before)
            if(!dsu2.sameSet(edge.u,edge.v)&&
                    (dsu2.find(edge.u)==leaf||dsu2.find(edge.v)==leaf)){
                cout<<edge.i;
                edges_before.erase(edge);
                break;
            }
        cout<<" ";
        for(auto edge:edges_after)
            if(!dsu2.sameSet(edge.u,edge.v)&&
               (dsu2.find(edge.u)==leaf||dsu2.find(edge.v)==leaf)){
                cout<<edge.i;
                dsu2.join(edge.u,edge.v);
                edges_before.insert(edge);
                break;
            }
        cout<<"\n";
    }
}