#include<bits/stdc++.h>
using namespace std;
#define lowbit(x) x&(-x)
#define endl '\n'
const int inf = 1000000005;
int n,m,a,b;
int in[300005],out[300005];
struct edge{
	int to,fl,id;
}e[4000005];
vector<int>p[1000005];vector<pair<int,int> >p1[300005],p2[300005];
bool can[1000005],vis[300005];
int dis[1000005],cur[1000005];int tot,s,t,head = 1;
inline void add(int a,int b,int c,int id){
	e[++head].to = b,e[head].fl = c;e[head].id = id;
	p[a].push_back(head);
	e[++head].to = a,e[head].fl = 0;e[head].id = id;
	p[b].push_back(head);return;
}
bool bfs(){
	for(int i = 1;i<=tot;i++)dis[i] = inf,cur[i] = 0;
	queue<int>q;
	q.push(s);dis[s] = 0;
	//cout << s << endl;
	while(!q.empty()){
		int now = q.front();q.pop();
		//cout << now << endl;
		for(int i =0;i<p[now].size();i++){
			int to = e[p[now][i]].to,fl = e[p[now][i]].fl;
			//	cout << " " << to << endl;
			if(!fl)continue;
			if(dis[now]+1<dis[to]){
				dis[to] = dis[now]+1;
				q.push(to);
			}
		}
	}return (dis[t]<inf);
}inline int dfs(int now,int f){
	if(now == t or !f)return f;
	int res = 0;
	for(int i = cur[now];i<p[now].size();i++){
		cur[now] = i;
		int to = e[p[now][i]].to,fl = e[p[now][i]].fl,nw = 0;
		if(!fl or dis[now]+1!=dis[to])continue;
		if(nw = dfs(to,min(f,fl))){
			res+=nw,f-=nw;
			e[p[now][i]].fl-=nw,e[p[now][i]^1].fl+=nw;
			if(!f)break;
		}
	}return res;
}int Dinic(){
	int ans = 0;
	while(bfs()){
		//	cout << 1 << endl;
		ans+=dfs(s,inf);
	}return ans;
}
signed main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	cin>>n>>m>>a>>b;
	for(int i = 1;i<=m;i++){
		int x,y;cin >> x >> y;
		out[x]++,in[y]++;p1[x].push_back({y,i});
	}int t1 =0,t2=0;
	for(int i =1;i<=n;i++){
		if(in[i] == 0)t1++;
		if(out[i] == 0)t2++;
	}//cout << t1 << " " << t2 << endl;
	if(t1 !=1 or t2!=1 or in[a]!=0 or out[b]!=0){
		cout << "NO" << endl;return 0;
	}tot = n*2+2;s = n*2+1,t = n*2+2;
	for(int i = 1;i<=n;i++){
		if(out[i]>1)add(s,i,out[i]-1,0);
	}for(int i = 1;i<=n;i++){
		if(i!=a)add(i+n,t,1,0);
	}for(int i = 1;i<=n;i++){
		for(int j = 0;j<p1[i].size();j++){
			add(i,p1[i][j].first+n,1,p1[i][j].second);
		}
	}int res = Dinic();vector<int>ans1,ans2;
	//cout << res << endl;
	if(res!=n-1){
		cout << "NO" << endl;
	}else{
		for(int i = 3;i<=head;i+=2){
			if(e[i].id!=0 and e[i].fl!=0){
				ans1.push_back(e[i].id);can[e[i].id] = 1;
			}
		}for(int i= 1;i<=n;i++){
			for(int j = 0;j<p1[i].size();j++){
				int to = p1[i][j].first,id = p1[i][j].second;
				if(can[id])continue;
				p2[to].push_back({i,id});
			}
		}queue<int>q;q.push(b);vis[b] = 1;
		while(!q.empty()){
			int now = q.front();q.pop();
			for(int i = 0;i<p2[now].size();i++){
				int to = p2[now][i].first,id = p2[now][i].second;
				if(vis[to] == 0){
					vis[to] = 1;ans2.push_back(id);q.push(to);
				}
			}
		}cout << "YES" << endl;
		for(int i =0;i<ans1.size();i++)cout << ans1[i] << ' ';cout << endl;
		for(int i =0;i<ans2.size();i++)cout << ans2[i] << ' ';cout << endl;
	}
	return 0;
}