#include <iostream>
#include <vector>
#include <queue>
#include <cstring>
#include <algorithm>

#define LL  long long
#define REP(i, n) for(int i = 0;i < (int)(n);i++)
#define ALL(x) (x).begin(),(x).end()

using namespace std;

struct Edge{
	int to,cap,rev,no;
	Edge(int t,int c,int r,int n){
		to = t;
		cap = c;
		rev = r;
		no = n;
	}
};

typedef vector<Edge> Edges;
typedef vector<Edges> Graph;

void addEdge(int from,int to,int cap,int no,Graph &g){
	g[from].push_back(Edge(to,cap,g[to].size(),no));
	g[to].push_back(Edge(Edge(from,0,g[from].size()-1,-1)));
}

int N,M;
Graph g;

int used[305];
int level[305];

void levelize(int s){
	level[s] = 0;
	queue<int> q;q.push(s);
	while(!q.empty()){
		int n = q.front();q.pop();
		for(Edges::iterator it=g[n].begin() ; it!=g[n].end() ; it++){
			if(it->cap>0 && level[it->to]<0){
				level[it->to] = level[n]+1;
				q.push(it->to);
			}
		}
	}
}

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

int dinic(int s,int t){
	int res = 0;
	const int INF = 1<<30;
	while(true){
		memset(level,-1,sizeof(level));
		levelize(s);
		if(level[t]<0)break;
		memset(used,0,sizeof(used));
		for(int f;(f=augment(s,t,INF))>0 ; res +=f);
	}
	return res;
}

int main(void)
{
	while(~scanf("%d%d",&N,&M)){
		g.assign(N,Edges(0,Edge(0,0,0,0)));
		REP(i,M){
			int x,y;
			scanf("%d%d",&x,&y);
			addEdge(x-1,y-1,1,-1,g);
			addEdge(y-1,x-1,1,i+1,g);
		}
		int S,T;
		scanf("%d%d",&S,&T);
		int f = dinic(S-1,T-1);
		vector<int> edge;
		REP(i,N){
			for(int j=0 ; j<(int)g[i].size() ; j++){
				if(g[i][j].no>0 && g[i][j].cap==0){
					edge.push_back(g[i][j].no);
				}
			}
		}
		printf("%d\n%d\n",f,edge.size());
		REP(i,edge.size()){
			printf("%d\n",edge[i]);
		}
	}
	return 0;
}