#include "bits/extc++.h"

using namespace std;

template <typename T, typename... U>
void dbgh(const T& t, const U&... u) {
    cerr << t;
    ((cerr << " | " << u), ...);
    cerr << endl;
}

#ifdef DEBUG
#define dbg(...)                                           \
    cerr << "L" << __LINE__ << " [" << #__VA_ARGS__ << "]" \
         << ": ";                                          \
    dbgh(__VA_ARGS__)
#else
#define cerr   \
    if (false) \
    cerr
#define dbg(...)
#endif

#define endl "\n"
#define long int64_t
#define sz(x) int(std::size(x))

constexpr int MAXN = 3e3 + 5;

int n, m, edges[MAXN][3], targ;
bool is_tree[MAXN];
pair<int, int> ans;
vector<pair<int, int>> graph[MAXN];

void dfs(int u, int p, pair<int, int> cmx) {
    if (u == targ) {
        ans = cmx;
        return;
    }

    for (auto& [v, ei] : graph[u]) {
        if (v == p) {
            continue;
        }
        dfs(v, u, max(cmx, {edges[ei][2], ei}));
    }
}

pair<int, int> max_path(int u, int v) {
    for (int i = 0; i < n; i++) {
        graph[i].clear();
    }
    for (int i = 0; i < m; i++) {
        if (!is_tree[i]) {
            continue;
        }
        auto& [u, v, _w] = edges[i];
        graph[u].emplace_back(v, i);
        graph[v].emplace_back(u, i);
    }

    targ = v;
    dfs(u, -1, {INT_MIN, -1});
    return ans;
}

void solve() {
    cin >> n >> m;
    for (int i = 0; i < m; i++) {
        auto& [u, v, w] = edges[i];
        cin >> u >> v >> w;
        u--;
        v--;
    }
    fill_n(is_tree, n - 1, true);

    vector<pair<int, int>> s_edges;
    for (int i = 0; i < m; i++) {
        s_edges.emplace_back(edges[i][2], i);
    }
    sort(begin(s_edges), end(s_edges));

    vector<pair<int, int>> ans;
    for (auto& [w, ei] : s_edges) {
        if (is_tree[ei]) {
            continue;
        }

        auto& [u, v, _w] = edges[ei];
        auto [nw, nei] = max_path(u, v);

        dbg(w, ei, nw, nei);
        if (w < nw) {
            swap(is_tree[ei], is_tree[nei]);
            ans.emplace_back(nei, ei);
        }
    }

    cout << sz(ans) << endl;
    for (auto& [a, b] : ans) {
        cout << a + 1 << " " << b + 1 << endl;
    }
}

int main() {
    cin.tie(nullptr);
    cin.exceptions(ios::failbit);
    ios_base::sync_with_stdio(false);
    solve();
}