#include <cassert>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <functional>
#include <iostream>
#include <limits>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

using Int = long long;

template <class T1, class T2> ostream &operator<<(ostream &os, const pair<T1, T2> &a) { return os << "(" << a.first << ", " << a.second << ")"; };
template <class T> ostream &operator<<(ostream &os, const vector<T> &as) { const int sz = as.size(); os << "["; for (int i = 0; i < sz; ++i) { if (i >= 256) { os << ", ..."; break; } if (i > 0) { os << ", "; } os << as[i]; } return os << "]"; }
template <class T> void pv(T a, T b) { for (T i = a; i != b; ++i) cerr << *i << " "; cerr << endl; }
template <class T> bool chmin(T &t, const T &f) { if (t > f) { t = f; return true; } return false; }
template <class T> bool chmax(T &t, const T &f) { if (t < f) { t = f; return true; } return false; }


vector<int> uf;
int root(int u) {
  return (uf[u] < 0) ? u : (uf[u] = root(uf[u]));
}
bool connect(int u, int v) {
  u = root(u);
  v = root(v);
  if (u == v) return false;
  if (uf[u] > uf[v]) swap(u, v);
  uf[u] += uf[v];
  uf[v] = u;
  return true;
}


int N, M;
vector<int> A, B, W;

int main() {
  for (; ~scanf("%d%d", &N, &M); ) {
    A.resize(M);
    B.resize(M);
    W.resize(M);
    for (int i = 0; i < M; ++i) {
      scanf("%d%d%d", &A[i], &B[i], &W[i]);
      --A[i];
      --B[i];
    }
    
    vector<pair<int, int>> es(M);
    for (int i = 0; i < M; ++i) {
      es[i] = make_pair(W[i] << 1 | ((i < N - 1) ? 0 : 1), i);
    }
    sort(es.begin(), es.end());
    uf.assign(N, -1);
    vector<int> tar(M, 0);
    for (const auto &e : es) {
      const int i = e.second;
      if (connect(A[i], B[i])) {
        tar[i] = 1;
      }
    }
    
    vector<int> on(M, 0);
    for (int i = 0; i < N - 1; ++i) {
      on[i] = 1;
    }
    vector<pair<int, int>> ans;
    for (; ; ) {
      int im = -1;
      for (int i = 0; i < M; ++i) if (on[i] && !tar[i]) {
        im = i;
        break;
      }
      if (!~im) {
        break;
      }
      on[im] = 0;
      uf.assign(N, -1);
      for (int i = 0; i < M; ++i) if (on[i]) {
        connect(A[i], B[i]);
      }
      for (int i = 0; i < M; ++i) if (!on[i] && tar[i]) {
        if (root(A[i]) != root(B[i])) {
          on[i] = 1;
          ans.emplace_back(im, i);
          goto found;
        }
      }
      assert(false);
     found:{}
    }
    
    printf("%d\n", (int)ans.size());
    for (const auto &op : ans) {
      printf("%d %d\n", op.first + 1, op.second + 1);
    }
  }
  return 0;
}