Sem_1_Task_4

#include <iostream>
#include <vector>

const int maxn = 2e5 + 7;
std::vector <std::vector <int>> gr;
int d[maxn], dp[maxn];
bool used[maxn], is_cutpoint[maxn];

void dfs(int v, int p = -1) {
    used[v] = true;
    if (p != -1) d[v] = d[p] + 1;
    dp[v] = d[v];
    int power = 0;
    for (auto u : gr[v]) {
        if (!used[u]) {
            power++;
            dfs(u, v);
            dp[v] = std::min(dp[v], dp[u]);
            if (p != -1 && dp[u] >= d[v]) is_cutpoint[v] = true;
        }
        else if (u != p) {
            dp[v] = std::min(dp[v], d[u]);
        }
    }
    if (p == -1 && power > 1) is_cutpoint[v] = true;
}

signed main() {
    int n, m;
    std::cin >> n >> m;
    gr.resize(n + m);
    for (int i = 0; i < m; i++) {
        int u, v, p;
        std::cin >> u >> v >> p;
        u += m - 1;
        v += m - 1;
        p += m - 1;
        gr[u].push_back(i);
        gr[v].push_back(i);
        gr[p].push_back(i);
        gr[i].push_back(u);
        gr[i].push_back(v);
        gr[i].push_back(p);
    }
    dfs(0);
    std::vector<int> ans;
    for (int i = 0; i < m; i++) {
        if (is_cutpoint[i]) ans.push_back(i + 1);
    }
    std::cout << ans.size() << "\n";
    for (auto x : ans) std::cout << x << "\n";
}