using System;
using System.Collections.Generic;


namespace Dag
{
	struct Vertex{
		public List<int> neighbours;
		public bool visited;
		public bool finished;
		public int coins;
		public int coinsToEnd;
		public int loopsTo;
		public int coinsToLoop;
		public int time;
		public bool printed;
		public bool hasCoin;
		public bool printDFSD;

	};
	class Program
	{
		static void PrintLoop(int k,int target, Vertex[] graph){
			foreach(int l in graph[k].neighbours){
				if(graph[l].loopsTo == target && graph[k].time < graph[l].time){
					PrintLoop(l,target,graph);
				}
			}
			if(graph[k].hasCoin && !graph[k].printed){
				Console.Write($"{k+1} ");
				graph[k].printed = true;
				graph[k].coins--;
			}
		}
		static void PrintDFS(int k,Vertex[] graph){
			Console.WriteLine($"In PrintDFS: {k}");
			graph[k].printDFSD = true;
			if(graph[k].hasCoin && !graph[k].printed){
				graph[k].printed = true;
				Console.Write($"{k+1} ");
			}
			if(k==99){
				Console.WriteLine($"76 loop: {graph[76].loopsTo}");
			}
			bool chosen =false;
			foreach(int l in graph[k].neighbours){
				if(graph[l].loopsTo == k ){
					//Console.WriteLine($"PrintLoop: {l} {k}");
					PrintLoop(l,k,graph);
				}
				if(k==10){
					Console.WriteLine($"k coinsToEnd: {graph[k].coinsToEnd}, l coinsToEnd : {graph[l].coinsToEnd}, k coins: {graph[k].coins}");
				}
				if((!chosen) && !graph[l].printDFSD && graph[l].coinsToEnd == graph[k].coinsToEnd - graph[k].coins ){
					PrintDFS(l,graph);
					chosen = true;
				}
			}
			//Console.WriteLine($"Out PrintDFS: {k}");
		}
		static int Earliest(Vertex[] graph, int a,int b){
			if(a==-1)return b;
			if(b==-1)return a;
			return graph[a].time <
					graph[b].time ? a : b;
		}
		static int DFS(int k,Vertex[] graph,int time,int n){
			if(k==10)
				Console.WriteLine($"We arrived at {k}, 98 is visited {graph[98].visited}, 98 is finished {graph[98].finished}\n");
			graph[k].visited = true;
			graph[k].coinsToEnd = -1;
			graph[k].coinsToLoop = -1;
			graph[k].loopsTo = -1;
			graph[k].time = time;
			if(k==n-1){
				graph[k].coinsToEnd = 0;
			}
			foreach(int l in graph[k].neighbours){
				if(graph[l].finished){
					graph[k].coinsToEnd = Math.Max(graph[l].coinsToEnd,
						graph[k].coinsToEnd);
				}else if(graph[l].visited){
					if(graph[k].loopsTo==-1)graph[k].coinsToLoop=0;
					graph[k].loopsTo = Earliest(graph, graph[k].loopsTo, l);
				}
				else{
					time = DFS(l,graph,time+1,n);
					graph[k].coinsToEnd = Math.Max(graph[l].coinsToEnd,
						graph[k].coinsToEnd);
					if(graph[l].loopsTo == k){
						graph[k].coins += graph[l].coinsToLoop;
					}else if(graph[k].loopsTo==-1){
						graph[k].loopsTo = graph[l].loopsTo;
						graph[k].coinsToLoop = graph[l].coinsToLoop;
					}else if(graph[l].loopsTo!=-1){
						graph[k].loopsTo = Earliest(graph,graph[k].loopsTo , graph[l].loopsTo);
						graph[k].coinsToLoop += graph[l].coinsToLoop;
					}
				}
				
			}
			if(k==10){
				Console.WriteLine($"coinsToEnd of 10 before: {graph[k].coinsToEnd}");
				Console.WriteLine($"loopsTo of 10 before: {graph[k].loopsTo}");
			}
			if(graph[k].loopsTo!=-1){
				graph[k].coinsToLoop+=graph[k].coins;
			}else if(graph[k].coinsToEnd!=-1){
				graph[k].coinsToEnd+=graph[k].coins;
			}
			if(k==10){
				Console.WriteLine($"coinsToEnd of 10 after: {graph[k].coinsToEnd}");
			}
			//graph[k].coinsToEnd += graph[k].coins;
			//if(graph[k].coinsToLoop !=-1)
			//	graph[k].coinsToLoop += graph[k].coins;
			graph[k].finished = true;
			
			return time;
		}
		static void Main(string[] args)
		{
			string[] threeNumbers = Console.ReadLine().Split(' ');
			int n = Int32.Parse(threeNumbers[0]);
			int m = Int32.Parse(threeNumbers[1]);
			int s = Int32.Parse(threeNumbers[2]);
	
			Vertex[] graph = new Vertex[n];
			for(int i =0; i<n ;i++){
				graph[i].neighbours = new List<int>();
				graph[i].visited =false;
				graph[i].finished =false;
				graph[i].printed =false;
				graph[i].coins =0;
				graph[i].hasCoin =false;
			}
		
			for(int j =0; j<m ;j++){
				string[] twoNumbers = Console.ReadLine().Split(' ');
				int a = Int32.Parse(twoNumbers[0]);
				int b = Int32.Parse(twoNumbers[1]);
		
				graph[a-1].neighbours.Add(b-1);
			}
			string[] coins = Console.ReadLine().Split(' ');
			for(int k = 0; k<s; k++){
				int index = Int32.Parse(coins[k])-1;
				graph[index].coins=1;
				graph[index].hasCoin=true;
			}
			DFS(0, graph, 0, n);

			//for(int i=0; i<n; i++){
			//	Console.WriteLine($"{graph[i].coins}, {graph[i].coinsToEnd} {graph[i].loopsTo}, {graph[i].coinsToLoop}");
			//}
			//for(int i =0; i<n; i++){
			//	Console.WriteLine($"Node {i+1}");
			//	Console.WriteLine($"Loop ({graph[i].loopsTo+1},{graph[i].coinsToLoop})");
			//	Console.WriteLine($"End {graph[i].coinsToEnd}");
			//	Console.WriteLine($"Tim {graph[i].time}");
			//	Console.WriteLine();
			//}
			if(graph[0].coinsToEnd==-1)Console.WriteLine(0);
			else Console.WriteLine(graph[0].coinsToEnd);
			if(graph[0].coinsToEnd>0){
				PrintDFS(0,graph);
				Console.WriteLine();
			}
		}
	}
}