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

std::vector<std::vector<std::pair<int, int>>> a;
std::vector<int> tin, bridges;
int timer = 0;

int dfs(int i, int prev) {
    if (tin[i] != 0)
        return tin[i];
    ++timer;
    tin[i] = timer;
    int tmp_time = tin[i];
    for (auto x : a[i])
        if (x.first != prev) {
            int t = dfs(x.first, i);
            if (t > tin[i])
                bridges.push_back(x.second);
            tmp_time = std::min(t, tmp_time);
        }
    tin[i] = tmp_time;
    return tmp_time;
}

int main() {
    int n, m;
    std::cin >> n >> m;
    a.resize(n);
    tin.resize(n, 0);
    for (int i = 1; i != m + 1; ++i) {
        int x, y;
        std::cin >> x >> y;
        --x;
        --y;
        a[x].push_back(std::make_pair(y, i));
        a[y].push_back(std::make_pair(x, i));
    }

    for (int i = 0; i != n; ++i)
        if (tin[i] == 0)
            dfs(i, -1);

    sort(bridges.begin(), bridges.end());
    std::cout << bridges.size() << std::endl;
    for (auto x : bridges)
        std::cout << x << " ";
    system("pause");
}