#include <bits/stdc++.h>

using namespace std;

#define rep(i, n) for (int i = 0; i < int(n); ++i)

struct MaxFlow {
  struct Edge {int to, cap, rev;};

  const static int INF = 1e9;

  int v;
  vector<vector<Edge> > g;
  vector<int> level, iter;

  MaxFlow() : v(0) {}

  int next() {
    g.push_back(vector<Edge>());
    level.push_back(0);
    iter.push_back(0);
    return v++;
  }
  
  void add_edge(int from, int to, int cap) {
    g[from].push_back((Edge){to, cap, int(g[to].size())});
    g[to].push_back((Edge){from, cap, int(g[from].size()) - 1});
  }

  void bfs(int s) {
    fill(level.begin(), level.end(), -1);
    level[s] = 0;
    queue<int> que;
    que.push(s);
    while (!que.empty()) {
      int v = que.front();
      que.pop();
      rep (i, g[v].size()) {
	Edge &e = g[v][i];
	if (e.cap == 0 || level[e.to] >= 0) continue;
	level[e.to] = level[v] + 1;
	que.push(e.to);
      }
    }
  }

  int dfs(int v, int t, int f) {
    if (v == t) return f;
    for (int &i = iter[v]; i < int(g[v].size()); ++i) {
      Edge &e = g[v][i];
      if (e.cap == 0 || level[v] >= level[e.to]) continue;
      int d = dfs(e.to, t, min(f, e.cap));
      if (d == 0) continue;
      e.cap -= d;
      g[e.to][e.rev].cap += d;
      return d;
    }
    return 0;
  }

  int run(int s, int t) {
    int flow = 0, f;
    while (true) {
      bfs(s);
      if (level[t] < 0) return flow;
      fill(iter.begin(), iter.end(), 0);
      while ((f = dfs(s, t, INF)) > 0) flow += f;
    }
  }
};

int main() {
  int n, m;
  cin >> n >> m;
  MaxFlow mf;
  rep (i, n) mf.next();
  vector<pair<int, int> > edge;
  rep (i, m) {
    int x, y;
    cin >> x >> y;
    --x; --y;
    mf.add_edge(x, y, 1);
    edge.push_back(make_pair(x, y));
  }
  int s, t;
  cin >> s >> t;
  --s; --t;
  cout << mf.run(s, t) << endl;
  vector<int> res;
  rep (i, m) {
    bool found = false;
    rep (j, mf.g[edge[i].second].size()) if (mf.g[edge[i].second][j].to == edge[i].first && mf.g[edge[i].second][j].cap == 0) found = true;
    if (found) res.push_back(i + 1);
  }
  cout << res.size() << endl;
  rep (i, res.size()) cout << res[i] << endl;
}