// ki bood ke goft Ghatinga?

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<pii,int> ppiii;

// vectors and Sets:
#define vc vector
#define pb push_back
#define all(c) (c).begin(), (c).end()

// pairs
#define mp make_pair
#define fr first
#define sc second

// execution time check and Debug
#define StartEX clock_t startExeTime = clock();
#define EndEX clock_t endExeTime = clock();
#define ExTime cerr << "\nTotal Execution Time is: " << double(-double(startExeTime)+double(endExeTime)) / CLOCKS_PER_SEC;
#define debug(x) cerr << #x << " : " << x << '\n'
#define endl "\n"

// time optimization
#define Heh ios::sync_with_stdio(false);cin.tie(0);
#define Bah ios::sync_with_stdio(false);
#pragma GCC optimize("Ofast")
// #pragma GCC target("avx,avx2,fma")

// useful functions
ll pw(ll a,ll b){
  ll ret = 1;
  ll mul = a;
  while(b > 0){
	if(b&1)
	  ret = (ret * mul);
	mul = (mul * mul);
	b >>= 1;
  }
  return ret;
}
ll pw(ll a,ll b,ll mod){
  ll ret = 1;
  ll mul = a;
  while(b > 0){
	if(b&1)
	  ret = (ret * mul) % mod;
	mul = (mul * mul) % mod;
	b >>= 1;
  }
  return ret;
}

ll to_int(string s){
  ll ret = 0;
  for(int i = 0 ; i < (int)s.size() ; i++) ret = 10 * ret + s[i] - '0';
  return ret;
}

bool deq(ld a , ld b){return (abs(a-b) < 0.000001);} // 10 ^ -6

const int MAXM = 3e3 + 33;

int n , m;

int par[MAXM] , rnk[MAXM];
int get(int v){return par[v] = (par[v] == v ? v : get(par[v]));}
void uni(int a , int b){
  a = get(a) , b = get(b);
  if(a == b) return;
  if(rnk[a] < rnk[b]) swap(a , b);
  par[b] = a;
  rnk[a] += (rnk[a] == rnk[b]);
}

struct ed{
  int u , v , w;
  int id;

  bool operator<(ed x){
    return w < x.w;
  }
};

int main()
{
  Heh;
  cin >> n >> m;
  ed es[m] , ses[m] , nes[m];
  for(int i = 0 ; i < m ; i++){
    int u , v , w;
    cin >> u >> v >> w;
    u-- , v--;
    es[i] = {u , v , w , i};
    ses[i] = es[i];
    nes[i] = es[i];
  }
  sort(es , es + n-1);
  sort(ses , ses + m);
  vc<int> add , rem;
  for(int i = 0 ; i < n ; i++) par[i] = i , rnk[i] = 0;
  int pt1 = 0 , pt2 = 0;
  vc<pii> bs;
  while(pt1 < n-1 or pt2 < m){
    if(pt2 == m or (pt1 < n-1 and es[pt1].w <= ses[pt2].w)){
      if(get(es[pt1].u) == get(es[pt1].v)){
	rem.pb(es[pt1].id);
      }
      else{
	uni(es[pt1].u , es[pt1].v);
	bs.pb({es[pt1].u , es[pt1].v});
      }
      pt1++;
    }
    else{
      if(get(ses[pt2].u) != get(ses[pt2].v)){
	add.pb(ses[pt2].id);
	uni(ses[pt2].u , ses[pt2].v);
      }
      pt2++;
    }
  }
  cout << add.size() << endl;
  for(int ri : rem){
    for(int i = 0 ; i < n ; i++) par[i] = i , rnk[i] = 0;
    for(auto [u , v] : bs) uni(u , v);

    uni(nes[ri].u , nes[ri].v);
    int sai = -1;
    for(int ai : add){
      if(get(nes[ai].u) == get(nes[ai].v)){
	cout << ri+1 << " " << ai+1 << endl;
	sai = ai;
	break;
      }
      uni(nes[ai].u , nes[ai].v);
    }

    bs.pb({nes[sai].u , nes[sai].v});
    
    vc<int> nadd;
    for(int ai : add){
      if(ai != sai) nadd.pb(ai);
    }
    add = nadd;
  }
}

// ki seda kard Patinga?