#include <iostream>
#include <vector>
#include <queue>
#include <climits>
#include <unordered_set>
#include <unordered_map>
#include <algorithm>

/* clang-format off */
static __attribute__((unused)) void redir(const std::string str) { std::freopen((str + ".in").c_str(), "r", stdin); std::freopen((str + ".out").c_str(), "w", stdout); }
static void fast_io() { std::ios_base::sync_with_stdio(false); std::cin.tie(nullptr); std::cout.tie(nullptr); }
template<typename T> static void read(T& var) { std::cin >> var; }
template<typename T, typename... Ts> static void read(T& var, Ts&... vars) { read(var); read(vars...); }
/* clang-format on */

struct pair_hash
{
        template<class T1, class T2>
        std::size_t operator()(const std::pair<T1, T2>& pair) const
        {
                return std::hash<T1>()(pair.first) ^ std::hash<T2>()(pair.second);
        }
};

using adj_t = std::vector<std::vector<std::pair<int, int>>>;
using mat_t = std::vector<std::vector<int>>;
using uset = std::unordered_set<int>;

static adj_t adj;
static std::unordered_map<std::pair<int, int>, int, pair_hash> edges_idx;
static int N;
static int M;

static void dfs(const int src, std::vector<char>& vis, uset& p, bool inverted,
                const mat_t& capacity, const mat_t& flow)
{
        vis[src] = true;
        p.insert(src);

        for(const auto& e : adj[src])
        {
                const int v = e.first;

                if(vis[v])
                {
                        continue;
                }

                if(!inverted && flow[src][v] == capacity[src][v])
                {
                        continue;
                }

                if(inverted && flow[v][src] == capacity[v][src])
                {
                        continue;
                }

                dfs(v, vis, p, inverted, capacity, flow);
        }
};

static std::vector<int> bfs(const int src)
{
        std::vector<int> dists(N + 1, -1);
        std::queue<int> q;

        q.push(src);
        dists[src] = 0;

        while(!q.empty())
        {
                const int u = q.front();
                q.pop();

                for(const auto& e : adj[u])
                {
                        const int v = e.first;

                        if(dists[v] != -1)
                        {
                                continue;
                        }

                        dists[v] = dists[u] + 1;
                        q.push(v);
                }
        }

        return dists;
}

static void maxflow(const int src, const int dest)
{
        mat_t capacity(N + 1, std::vector<int>(N + 1, 0));
        mat_t flow(N + 1, std::vector<int>(N + 1, 0));
        for(int node = 1; node <= N; ++node)
        {
                for(const auto& e : adj[node])
                {
                        capacity[node][e.first] = std::max(capacity[node][e.first], e.second);
                }
        }

        const auto bfs_parents = [&]() -> std::vector<int>
        {
                std::vector<char> visited(N + 1, false);
                std::vector<int> parent(N + 1, -1);
                std::queue<int> q;

                q.push(src);
                visited[src] = true;

                while(!q.empty())
                {
                        const auto current = q.front();
                        q.pop();

                        for(const auto& neigh : adj[current])
                        {
                                if(visited[neigh.first] || capacity[current][neigh.first] <=
                                                               flow[current][neigh.first])
                                {
                                        continue;
                                }

                                if(neigh.first == dest)
                                {
                                        parent[dest] = current;
                                        return parent;
                                }

                                q.push(neigh.first);
                                parent[neigh.first] = current;
                                visited[neigh.first] = true;
                        }
                }

                return parent;
        };

        while(true)
        {
                const auto parent = bfs_parents();

                if(parent[dest] == -1)
                {
                        break;
                }

                int path_min_cap = INT_MAX;
                for(int v = dest; v != src; v = parent[v])
                {
                        const int u = parent[v];
                        path_min_cap = std::min(path_min_cap, capacity[u][v] - flow[u][v]);
                }

                for(int v = dest; v != src; v = parent[v])
                {
                        const int u = parent[v];

                        flow[u][v] += path_min_cap;
                        flow[v][u] -= path_min_cap;
                }
        }

        std::vector<char> visited(N + 1, false);
        uset left;
        uset right;

        dfs(1, visited, left, false, capacity, flow);
        dfs(N, visited, right, true, capacity, flow);

        std::vector<int> solution;
        for(const int u : left)
        {
                for(const auto& e : adj[u])
                {
                        const int v = e.first;

                        if(flow[u][v] == capacity[u][v] && right.find(v) != right.end())
                        {
                                solution.push_back(edges_idx[std::make_pair(u, v)]);
                        }
                }
        }

        std::sort(solution.begin(), solution.end());
        std::cout << solution.size() << '\n';
        for(int el : solution)
        {
                std::cout << el << '\n';
        }
}

struct edge_t
{
        int u, v, w;
};

int main()
{
#ifndef CLOCAL
        redir("critice");
#endif
        fast_io();
        read(N, M);

        adj.resize(N + 1);
        std::vector<edge_t> edges;
        for(int i = 0; i < M; ++i)
        {
                int u, v, w;
                read(u, v, w);

                adj[u].push_back({v, w});
                adj[v].push_back({u, w});

                edges.push_back({u, v, w});
        }

        const auto dists = bfs(1);

        int k = 0;
        adj.clear();
        adj.resize(N + 1);
        for(const auto& edge : edges)
        {
                const int u = edge.u;
                const int v = edge.v;
                const int w = edge.w;

                if(dists[u] == dists[v])
                {
                        adj[u].push_back({v, w});
                        adj[v].push_back({u, w});

                        edges_idx[std::make_pair(u, v)] = k + 1;
                        edges_idx[std::make_pair(v, u)] = k + 1;
                }
                else if(dists[u] < dists[v])
                {
                        adj[u].push_back({v, w});
                        adj[v].push_back({u, 0});

                        edges_idx[std::make_pair(u, v)] = k + 1;
                }
                else
                {
                        adj[v].push_back({u, w});
                        adj[u].push_back({v, 0});

                        edges_idx[std::make_pair(v, u)] = k + 1;
                }

                ++k;
        }

        maxflow(1, N);
}