#include <iostream>
#include <vector>
#include <cmath>
#include <ctime>
#include <cassert>
#include <cstdio>
#include <queue>
#include <set>
#include <map>
#include <fstream>
#include <cstdlib>
#include <string>
#include <cstring>
#include <algorithm>
#include <numeric>

#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define forn(i, n) for (int i = 0; i < (int)(n); ++i)
#define for1(i, n) for (int i = 1; i <= (int)(n); ++i)
#define ford(i, n) for (int i = (int)(n) - 1; i >= 0; --i)
#define fore(i, a, b) for (int i = (int)(a); i <= (int)(b); ++i)

using namespace std;

typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<pii> vpi;
typedef vector<vi> vvi;
typedef long long i64;
typedef vector<i64> vi64;
typedef vector<vi64> vvi64;

template<class T> bool uin(T &a, T b) { return a > b ? (a = b, true) : false; }
template<class T> bool uax(T &a, T b) { return a < b ? (a = b, true) : false; }

struct TEdge {
    int to, w, id;

    TEdge(int to = 0, int w = 0, int id = 0)
        : to(to)
        , w(w)
        , id(id)
    {
    }
};

typedef vector< vector<TEdge> > TGraph;

void dfs0(int v, TGraph &e, vi &vis, vi &tre) {
    vis[v] = 1;
    for (TEdge w: e[v]) {
        if (w.w || vis[w.to]) continue;
        tre.pb(w.id);
        dfs0(w.to, e, vis, tre);
    }
}

void dfs_ord(int v, TGraph &e, vi &vis, vi &ord) {
    if (vis[v]) return;
    vis[v] = 1;
    for (TEdge w: e[v]) dfs_ord(w.to, e, vis, ord);
    ord.pb(v);
}

void dfs_comp(int v, TGraph &e, vi &vis, vi &comp, int cc) {
    if (vis[v]) return;
    comp[v] = cc;
    vis[v] = 1;
    for (TEdge w: e[v]) dfs_comp(w.to, e, vis, comp, cc);
}

void dfs_cc0(int v, TGraph &e, vi &vis, vi &comp, vi &tre) {
    if (vis[v]) return;
    vis[v] = 1;
    for (TEdge w: e[v]) {
        if (vis[w.to] || comp[w.to] != comp[v]) continue;
        tre.pb(w.id);
        dfs_cc0(w.to, e, vis, comp, tre);
    }
}

TGraph rev(TGraph g) {
    int n = g.size();
    TGraph rg(n);
    forn(i, n) for (TEdge w: g[i]) rg[w.to].pb(TEdge(i, w.w, w.id));
    return rg;
}

vi condense(TGraph &e) {
    int n = e.size();
    vi vis(n), ord;
    forn(i, n) dfs_ord(i, e, vis, ord);
    reverse(all(ord));
    vis.assign(n, 0);
    TGraph re = rev(e);
    vi comp(n);
    int cc = 0;
    for (int v: ord) {
        if (vis[v]) continue;
        dfs_comp(v, re, vis, comp, cc++);
    }
    return comp;
}

vi mst(int v, TGraph e) {
//    cerr << e.size() << '\n';
    int n = e.size();
    vi pot(n, 1e9);
    forn(i, n) for (TEdge w: e[i]) uin(pot[w.to], w.w);
    TGraph e0(n);
    forn(i, n) for (TEdge &w: e[i]) {
        w.w -= pot[w.to];
        if (!w.w) e0[i].pb(w);
    }
    vi vis(n);
    vi tre;
    dfs0(v, e0, vis, tre);
    if (tre.size() == n - 1) return tre;
    vi comp = condense(e0);
    int cc = *max_element(all(comp)) + 1;
    TGraph ne(cc);
    forn(i, n) for (TEdge w: e[i]) {
        if (comp[i] != comp[w.to]) ne[comp[i]].pb(TEdge(comp[w.to], w.w, w.id));
    }
    vi cmst = mst(comp[v], ne);
    set<int> cid(all(cmst));
    vis.assign(n, 0);
    dfs_cc0(v, e0, vis, comp, cmst);
    forn(i, n) for (TEdge w: e[i]) {
        if (cid.count(w.id)) dfs_cc0(w.to, e0, vis, comp, cmst);
    }
    return cmst;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.precision(10);
    cout << fixed;
#ifdef LOCAL_DEFINE
    freopen("input.txt", "rt", stdin);
#endif

    int N, M;
    cin >> N >> M;
    TGraph e(N);
    forn(i, M) {
        int x, y, z;
        cin >> x >> y >> z;
        --x; --y;
        e[x].pb(TEdge(y, z, i + 1));
    }
    vi ans = mst(0, e);
    cout << ans.size() << '\n';
    for (int x: ans) cout << x << ' ';
    cout << '\n';

#ifdef LOCAL_DEFINE
    cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
#endif
    return 0;
}