#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>

using namespace std;

int nredge[1001][1001];

struct FlowEdge {
    int v, u;
    long long cap, flow = 0;
    FlowEdge(int v, int u, long long cap) : v(v), u(u), cap(cap) {}
};

struct Dinic {
    const long long flow_inf = 1e18;
    vector<FlowEdge> edges;
    vector<vector<int>> adj;
    int n, m = 0;
    int s, t;
    vector<int> level, ptr;
    queue<int> q;
    vector<bool> viz1, vizn;

    Dinic(int n, int s, int t) : n(n), s(s), t(t) {
        adj.resize(n);
        level.resize(n);
        ptr.resize(n);
        viz1.resize(n);
        vizn.resize(n);
    }

    void add_edge(int v, int u, long long cap, int nr) {
        edges.emplace_back(v, u, cap);
        edges.emplace_back(u, v, 0);
        adj[v].push_back(m);
        adj[u].push_back(m + 1);
        if (u < v) swap(v, u);
        nredge[v][u] = nr;
        m += 2;
    }

    bool bfs() {
        while (!q.empty()) {
            int v = q.front();
            q.pop();
            for (int id : adj[v]) {
                if (edges[id].cap - edges[id].flow < 1)
                    continue;
                if (level[edges[id].u] != -1)
                    continue;
                level[edges[id].u] = level[v] + 1;
                q.push(edges[id].u);
            }
        }
        return level[t] != -1;
    }

    long long dfs(int v, long long pushed) {
        if (pushed == 0)
            return 0;
        if (v == t)
            return pushed;
        for (int& cid = ptr[v]; cid < (int)adj[v].size(); cid++) {
            int id = adj[v][cid];
            int u = edges[id].u;
            if (level[v] + 1 != level[u] || edges[id].cap - edges[id].flow < 1)
                continue;
            long long tr = dfs(u, min(pushed, edges[id].cap - edges[id].flow));
            if (tr == 0)
                continue;
            edges[id].flow += tr;
            edges[id ^ 1].flow -= tr;
            return tr;
        }
        return 0;
    }

    void flow() {
        long long f = 0;
        while (true) {
            fill(level.begin(), level.end(), -1);
            level[s] = 0;
            q.push(s);
            if (!bfs())
                break;
            fill(ptr.begin(), ptr.end(), 0);
            while (long long pushed = dfs(s, flow_inf)) {
                f += pushed;
            }
        }
    }

    void dfsCrit(int nod, int dir)
    {
        viz1[nod] = 1;
        for (auto id : adj[nod])
        {
            int n1 = edges[id].v, n2 = edges[id].u;
            if (dir == 1) swap(n1, n2);
            if (nod != n1) continue;

            if (edges[id].cap - edges[id].flow > 0)
            {
                dfs(n2, dir);
            }
        }
    }

    void findCrit()
    {
        vector<int> ansvec;
        dfsCrit(s, 0);
        dfsCrit(t, 1);
        for (int i = 1; i < n; i++)
        {
            for (int j = i + 1; j <= n; j++)
            {
                if (i == j) continue;
                if ((viz1[i] && !vizn[j]) || (!viz1[i] && vizn[j]))
                {
                    if (nredge[i][j]) ansvec.push_back(nredge[i][j]);
                }
            }
        }
        cout << ansvec.size() << '\n';
        sort(ansvec.begin(), ansvec.end());
        for (auto edge : ansvec) cout << edge << '\n';
    }
};

int main ()
{
    freopen("critice.in", "r", stdin);
    freopen("critice.out", "w", stdout);
    int n, m; cin >> n >> m;
    Dinic graf = Dinic(n + 1, 1, n);
    for (int i = 1; i <= m; i++)
    {
        int x, y, f; cin >> x >> y >> f;
        graf.add_edge(x, y, f, i);
    }
    graf.flow();
    graf.findCrit();

}