#include <vector>
#include <list>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <deque>
#include <algorithm>
#include <utility>
#include <functional>
#include <sstream>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <climits>
#include <cassert>
#include <memory>
#include <time.h>
using namespace std;
inline int toInt(string s) {int v; istringstream sin(s);sin>>v;return v;}
template<class T> inline string toString(T x) {ostringstream sout;sout<<x;return sout.str();}
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<string> vs;
typedef pair<int, int> pii;
typedef long long ll;
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(),(a).rend()
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
const double EPS = 1e-9;
const double PI  = acos(-1.0);


#define EACH(i,t,c) for(t::const_iterator i=(c).begin();i!=(c).end();++i)
typedef int Weight;
struct Edge {
  int src, dst;
  Weight weight;
  Edge(int src, int dst, Weight weight) :
    src(src), dst(dst), weight(weight) { }
};
bool operator < (const Edge &e, const Edge &f) {
  return e.weight != f.weight ? e.weight > f.weight : // !!INVERSE!!
    e.src != f.src ? e.src < f.src : e.dst < f.dst;
}
typedef vector<Edge> Edges;
typedef vector<Edges> Graph;

typedef vector<Weight> Array;
typedef vector<Array> Matrix;

const int INF=INT_MAX/10;

#define RESIDUE(s,t) (capacity[s][t]-flow[s][t])
Weight augment(const Graph &g, const Matrix &capacity, Matrix &flow,
    const vector<int> &level, vector<bool> &finished, int u, int t, Weight cur) {
  if (u == t || cur == 0) return cur;
  if (finished[u]) return 0;
  finished[u] = true;
  EACH(e, Edges, g[u]) if (level[e->dst] > level[u]) {
    Weight f = augment(g, capacity, flow, level, finished,
        e->dst, t, min(cur, RESIDUE(u, e->dst)));
    if (f > 0) {
      flow[u][e->dst] += f; flow[e->dst][u] -= f;
      finished[u] = false;
      return f;
    }
  }
  return 0;
}
Weight maximumFlow(const Graph &g, int s, int t, Matrix &flow) {
  int n = g.size();
  Matrix capacity(n, Array(n)); // adj. matrix
  REP(u,n) EACH(e,Edges,g[u]) capacity[e->src][e->dst] += e->weight;

  Weight total = 0;
  for (bool cont = true; cont; ) {
    cont = false;
    vector<int> level(n, -1); level[s] = 0; // make layered network
    queue<int> Q; Q.push(s);
    for (int d = n; !Q.empty() && level[Q.front()] < d; ) {
      int u = Q.front(); Q.pop();
      if (u == t) d = level[u];
      EACH(e, Edges, g[u]) if (RESIDUE(u,e->dst) > 0 && level[e->dst] == -1)
        Q.push(e->dst), level[e->dst] = level[u] + 1;
    }
    vector<bool> finished(n); // make blocking flows
    for (Weight f = 1; f > 0; ) {
      f = augment(g, capacity, flow, level, finished, s, t, INF);
      if (f == 0) break;
      total += f; cont = true;
    }
  }
  return total;
}

int main(){
	int n,m;
	cin>>n>>m;
	Graph g(n,Edges());
	Graph gNondir(n,Edges());
	vi x(m),y(m);
	REP(i,m){
		cin>>x[i]>>y[i],x[i]--,y[i]--;
		g[x[i]].push_back(Edge(x[i],y[i],1));
		gNondir[x[i]].push_back(Edge(x[i],y[i],1));
		gNondir[y[i]].push_back(Edge(y[i],x[i],1));
	}
	int start,goal;
	cin>>start>>goal,start--,goal--;

	Matrix flow(n, Array(n));
	Weight mf=maximumFlow(gNondir,start,goal,flow);
	cout<<mf<<endl;
	vi reversed;
	REP(i,m){
		if(flow[y[i]][x[i]]>0){
			reversed.push_back(i+1);
		}
	}
	cout<<reversed.size()<<endl;
	REP(i,reversed.size()){
		cout<<reversed[i]<<endl;
	}
}

Measured memory_bytes: 1800