using System;
using System.Collections.Generic;
using System.Collections;
using System.Collections.Specialized;
using System.Linq;
using System.Text;
using System.IO;
using System.Reflection;
using static System.Math;
using System.Numerics;
static class Program{
	const int mod=(int)1e9+7;
	static List<int>[] li;
	static void Main(){
		Sc sc=new Sc();
		var s=sc.Ia;
		int n=s[0],m=s[1];
		var g=sc.Ia;
		li=new List<int>[n+1];
		var h=new int[2][];
		var f=new int[2][];
		h[0]=new int[n+1];
		h[1]=new int[n+1];
		f[0]=new int[n+1];
		f[1]=new int[n+1];
		for(int i=1;i<=n;i++){
			li[i]=new List<int>();
			h[0][i]=h[1][i]=f[0][i]=f[1][i]=mod;
		}
		for(int i=0;i<m;i++){
			var e=sc.Ia;
			li[e[0]].Add(e[1]);
			li[e[1]].Add(e[0]);
		}
		var qu=new Queue<ValueTuple<int,int>>();
		qu.Enqueue(ValueTuple.Create(g[0],0));
		while(qu.Count>0){
			var e=qu.Dequeue();
			if(h[e.Item2&1][e.Item1]!=mod){continue;}
			h[e.Item2&1][e.Item1]=e.Item2;
			for(int j = 0;j<li[e.Item1].Count;j++) {
				if(h[(e.Item2+1)&1][li[e.Item1][j]]==mod){qu.Enqueue(ValueTuple.Create(li[e.Item1][j],e.Item2+1));}
			}
		}
		qu=new Queue<ValueTuple<int,int>>();
		qu.Enqueue(ValueTuple.Create(g[1],0));
		while(qu.Count>0){
			var e=qu.Dequeue();
			if(f[e.Item2&1][e.Item1]!=mod){continue;}
			f[e.Item2&1][e.Item1]=e.Item2;
			for(int j = 0;j<li[e.Item1].Count;j++) {
				if(f[(e.Item2+1)&1][li[e.Item1][j]]==mod){qu.Enqueue(ValueTuple.Create(li[e.Item1][j],e.Item2+1));}
			}
		}
		StringBuilder sb=new StringBuilder();
		int a=0;
		for(int i=1;i<=n;i++){
			if(h[0][i]+f[s[2]&1][i]<=s[2]||h[1][i]+f[(s[2]+1)&1][i]<=s[2]){
				a++;
				sb.Append(i+"\n");
			}
		}
		Console.WriteLine(a==0?-1:a);
		Console.Write(sb);
	}
}

public class Sc{
	public int I{get{return int.Parse(Console.ReadLine());}}
	public long L{get{return long.Parse(Console.ReadLine());}}
	public double D{get{return double.Parse(Console.ReadLine());}}
	public string S{get{return Console.ReadLine();}}
	public int[] Ia{get{return Array.ConvertAll(Console.ReadLine().Split(),int.Parse);}}
	public long[] La{get{return Array.ConvertAll(Console.ReadLine().Split(),long.Parse);}}
	public double[] Da{get{return Array.ConvertAll(Console.ReadLine().Split(),double.Parse);}}
	public string[] Sa{get{return Console.ReadLine().Split();}}
	public object[] Oa{get{return Console.ReadLine().Split();}}
	public int[] Ia2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),int.Parse);}}
	public int[] Ia3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),int.Parse);}
	public long[] La2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),long.Parse);}}
	public long[] La3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),long.Parse);}
	public double[] Da2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),double.Parse);}}
	public double[] Da3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),double.Parse);}
	public T[] Arr<T>(int n,Func<T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f();}return a;}
	public T[] Arr<T>(int n,Func<int,T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i);}return a;}
	public T[] Arr<T>(int n,Func<string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(Console.ReadLine().Split());}return a;}
	public T[] Arr<T>(int n,Func<int,string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i,Console.ReadLine().Split());}return a;}
}