#include <bits/stdc++.h>
#define isz(x) (int)(x).size()
struct Edge {
    int u, v, cost;
};
const int NMAX = 20020, INF = (int)1e9+7;
int nV;
std::vector<Edge> edges;
std::vector<int> adj[NMAX];
int dist[NMAX], from[NMAX];
void find_path(int s, int t, bool first) {
    std::fill(dist,dist+NMAX,INF);
    std::fill(from,from+NMAX, -1);
    std::deque<int> q = {s};
    dist[s] = 0;
    while (isz(q)) {
        auto u = q.front(); q.pop_front();
        for (int i : adj[u]) {
            const auto & e = edges[i];
            int v = e.u + e.v - u;
            if (dist[v] > dist[u] + e.cost) {
                if (e.cost == 0 && !first) { q.push_front(v); }
                else { q.push_back(v); }
                dist[v] = dist[u] + e.cost;
                from[v] = i;
            }
        }
    }
    while (from[t] != -1) {
        int id = from[t];
        auto &e = edges[id];
        e.cost++;
        t = e.u + e.v - t;
    }
}

int main() {
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(0);
    freopen("inevit.in", "rt", stdin);
    freopen("inevit.out", "wt", stdout);
    int nE; std::cin >> nV >> nE;
    for (int i = 0, u, v; i < nE; i++) {
        std::cin >> u >> v;
        edges.push_back(Edge{u,v,0});
        adj[u].push_back(i);
        adj[v].push_back(i);
    }
    find_path(1, nV, 1);
    find_path(1, nV, 0);
    int t = nV;
    std::vector<int> answ;
    while (from[t] != -1) {
        int id = from[t];
        const auto &e = edges[id];
        if (e.cost == 2) {
            answ.push_back(id + 1);
        }
        t = e.u + e.v - t;
    }
    std::reverse(answ.begin(),answ.end());
    std::cout << answ.size() << '\n';
    for (auto it : answ) std::cout << it << ' ';
    std::cout << std::endl;
    return 0;
}