#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#include <ctime>
#include <cmath>
#include <functional>
#include <cassert>
#include <complex>
#include <valarray>
using namespace std;

typedef pair<int, int> pii;
#define mp make_pair
#define X first
#define Y second

const int INF = (int)1e9 + 100;
const int N = 555;
const int M = 10100;
int n, m;
int cost[M];
int ed[M][2];
vector<pii> G[N];
vector<int> g[N], rg[N];
int ord[N];
int ordSz;
int col[N];
int C;
int minEdge[N];
bool used[N];
bool goodEdge[M];

void read()
{
    scanf("%d%d", &n, &m);
    for (int i = 0; i < m; i++)
    {
        int v, u, w;
        scanf("%d%d%d", &v, &u, &w);
        v--;u--;
        cost[i] = w;
        ed[i][0] = v;
        ed[i][1] = u;
        G[v].push_back(mp(u, i));
    }
    return;
}

void dfsOrd(int v)
{
    used[v] = 1;
    for (int u : g[v])
        if (!used[u])
            dfsOrd(u);
    ord[ordSz++] = v;
    return;
}
void dfsColor(int v)
{
    col[v] = C;
    for (int u : rg[v])
        if (col[u] == -1)
            dfsColor(u);
    return;
}

void dfsCheck(int v)
{
    used[v] = 1;
    for (pii e : G[v])
    {
        if (cost[e.second] != 0) continue;
        int u = e.first;
        if (!used[u])
        {
            goodEdge[e.second] = true;
            dfsCheck(u);
        }
    }
    return;
}
bool check(int sz, int V)
{
    for (int i = 0; i < sz; i++)
        used[i] = false;
    dfsCheck(V);
    for (int i = 0; i < sz; i++)
        if (!used[i])
        {
            for (int e = 0; e < m; e++)
                goodEdge[e] = false;
            return false;
        }
    return true;
}

void dfsAns(int v)
{
    used[v] = true;
    for (pii e : G[v])
    {
        if (cost[e.second] != 0) continue;
        int u = e.first;
        if (used[u] || col[v] != col[u]) continue;
        goodEdge[e.second] = true;
        dfsAns(u);
    }
    return;
}

void solve(int sz, int V)
{
    if (sz == 1) throw;
    for (int i = 0; i < sz; i++)
        minEdge[i] = INF;
    for (int v = 0; v < sz; v++)
        for (pii e : G[v])
            minEdge[e.first] = min(minEdge[e.first], cost[e.second]);
    for (int v = 0; v < sz; v++)
        for (pii e : G[v])
            if (e.first != V)
                cost[e.second] -= minEdge[e.first];
    if (check(sz, V))
        return;
    for (int v = 0; v < sz; v++)
    {
        g[v].clear();
        rg[v].clear();
    }
    for (int v = 0; v < sz; v++)
        for (pii e : G[v])
            if (e.first != V && cost[e.second] == 0)
            {
                g[v].push_back(e.first);
                rg[e.first].push_back(v);
            }
    ordSz = 0;
    for (int i = 0; i < sz; i++)
        used[i] = false;
    for (int v = 0; v < sz; v++)
        if (!used[v])
            dfsOrd(v);
    if (ordSz != sz) throw;
    reverse(ord, ord + sz);
    for (int v = 0; v < sz; v++)
        col[v] = -1;
    C = 0;
    for (int i = 0; i < sz; i++)
    {
        int v = ord[i];
        if (col[v] != -1) continue;
        dfsColor(v);
        C++;
    }
    if (C == sz) throw;
    vector<pii> NG[N];
    for (int i = 0; i < sz; i++)
        NG[i].clear();
    for (int v = 0; v < sz; v++)
        for (pii e : G[v])
        {
            int nv = col[v], nu = col[e.first];
            if (nv == nu) continue;
            NG[nv].push_back(mp(nu, e.second));
        }
    for (int v = 0; v < sz; v++)
        swap(G[v], NG[v]);
    int ncol[N];
    for (int v = 0; v < sz; v++)
        ncol[v] = col[v];
    solve(C, col[V]);
    for (int v = 0; v < sz; v++)
        col[v] = ncol[v];
    for (int v = 0; v < sz; v++)
        swap(G[v], NG[v]);
    for (int v = 0; v < sz; v++)
        used[v] = false;
    for (int v = 0; v < sz; v++)
        for (pii e : G[v])
        {
            int u = e.first;
            if (!used[u] && goodEdge[e.second])
                dfsAns(u);
        }
    return;
}

int main()
{
#ifdef LOCAL
    freopen ("input.txt", "r", stdin);
    freopen ("output.txt", "w", stdout);
    freopen ("err.txt", "w", stderr);
#endif

    read();
    solve(n, 0);
    printf("%d\n", n - 1);
    for (int i = 0; i < m; i++)
        if (goodEdge[i])
            printf("%d ", i + 1);
    printf("\n");

    return 0;
}