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

#define ll long long
#define all(x) x.begin(), x.end()
#define pb push_back
#define f first
#define s second

const int MAXN = 2005;

vector<int> adj[MAXN];
int comp[MAXN];


void dfs(int x, int p) {
    comp[x] = 1;
    for(int i:adj[x]) {
        if(i == p) continue;
        dfs(i,x);
    }
}
void populate(int x, int n) {
    for(int i=0; i<n; i++) comp[i] = 0;
    dfs(x,-1);
}

int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0);
    if (fopen("input.in", "r")) {
        freopen("input.in", "r", stdin);
        freopen("output.out", "w", stdout);
    }
    int n, m;
    cin>>n>>m;

    set<int> active;
    set<int> available;
    int eds[m][2];
    int wt[m];
    for(int i=0; i<m; i++){
        int u, v, w;
        cin>>u>>v>>w;
        u--; v--;
        eds[i][0] = u;
        eds[i][1] = v;
        wt[i] = w;
        if(i<n-1) active.insert(i);
        else available.insert(i);
    }   
    vector<pair<int, int>> ord;
    for(int i=0; i<n-1; i++) ord.pb({i, wt[i]});
    sort(all(ord));
    vector<pair<int, int>> res;
    for(auto p:ord) {
        int i = p.f;
        for(int e:active) {
            if(e == i) continue;
            adj[eds[e][0]].pb(eds[e][1]);
            adj[eds[e][1]].pb(eds[e][0]);
        }
        populate(0,n);
        for(int i=0; i<n; i++) adj[i].clear();
        int best = wt[i];
        int org = i;
        for(int e:available) {
            if(comp[eds[e][0]] == comp[eds[e][1]]) continue;
            if(wt[e] < best) {
                best = wt[e];
                org = e;
            }
        }
        if(org == i) continue;
        active.erase(active.find(i));
        active.insert(org);
        res.pb({i, org});
    }

    cout<<res.size()<<"\n";
    for(auto p:res){
        cout<<p.f+1<<" "<<p.s+1<<"\n";
    }
}

//  traverse edges in reverse order