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

using i64 = long long;

struct DSU {
    int n, cnt;
    vector<int> fa, sz;
    DSU(int n = 0) : n(n), cnt(n), fa(n), sz(n, 1) { iota(fa.begin(), fa.end(), 0); }
    int find(int u) { return u == fa[u] ? u : fa[u] = find(fa[u]); }
    bool join(int u, int v) {
        u = find(u), v = find(v);
        if (u != v) {
            // if (sz[u] < sz[v]) { swap(u, v); }
            sz[u] += sz[v];
            fa[v] = u;
            cnt--;
            return true;
        }
        return false;
    }
    bool same(int u, int v) { return find(u) == find(v); }
    int size(int u) { return sz[find(u)]; }
};

int main() {
    cin.tie(nullptr)->sync_with_stdio(false);
    
    auto solve = [&]() {
        int n, m;
        cin >> n >> m;

        vector<array<int, 4>> e(m);
        for (int j = 0; auto &[w, i, u, v] : e) {
            cin >> u >> v >> w;
            u--, v--;
            i = j++;
        }

        sort(e.begin(), e.end());
        
        DSU d(n);
        vector<int> mst(m), cur(m);
        fill(cur.begin(), cur.begin() + n - 1, true);
        
        for (auto [w, i, u, v] : e) {
            if (d.join(u, v)) {
                mst[i] = true;
            }
        }

        vector<pair<int, int>> ans;

        for (int ite = 0; ite < n - 1; ite++) {
            if (cur[ite] && !mst[ite]) {
                DSU d(n);
                for (auto [w, i, u, v] : e) {
                    if (cur[i] && i != ite) {
                        d.join(u, v);
                    }
                }
                for (auto [w, i, u, v] : e) {
                    if (mst[i] && !cur[i] && d.join(u, v)) {
                        ans.emplace_back(ite, i);
                        cur[ite] = false;
                        cur[i] = true;
                        break;
                    }
                }
            }
        }

        cout << ans.size() << '\n';
        for (auto [u, v] : ans) {
            cout << u + 1 << ' ' << v + 1 << '\n';
        }
    };

    solve();

    return 0;
}