content: package v116;
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.ArrayList;
  import java.util.LinkedList;
  import java.util.Queue;
  import java.util.StringTokenizer;
  
  
  public class PickUpSticks_UVa11686 {
  	
  	public static void main(String[] args) throws IOException 
  	{
  		Scanner sc = new Scanner(System.in);
  		PrintWriter out = new PrintWriter(System.out);
  		
  		while(true)
  		{
  			int N = sc.nextInt(), M = sc.nextInt();
  			if(N + M == 0)
  				break;
  			ArrayList<Integer>[] adjList = new ArrayList[N];
  			for(int i = 0; i < N; ++i)
  					adjList[i] = new ArrayList<Integer>();
  			
  			int[] deg = new int[N];
  			while(M-->0)
  			{
  				int u = sc.nextInt() - 1, v = sc.nextInt() - 1;
  				adjList[u].add(v);
  				deg[v]++;
  			}
  
  			Queue<Integer> q = new LinkedList<Integer>();
  			ArrayList<Integer> ans = new ArrayList<Integer>(N);
  			for(int i = 0; i < N; ++i)
  				if(deg[i] == 0)
  					q.add(i);
  			while(!q.isEmpty())
  			{
  				int u = q.remove();
  				ans.add(u);
  				for(int v: adjList[u])
  					if(--deg[v] == 0)
  						q.add(v);
  			}
  			
  			
  			if(ans.size() != N)
  				out.println("IMPOSSIBLE");
  			else
  			{
  				StringBuilder sb = new StringBuilder();
  				for(int x: ans)
  					sb.append(x+1+"\n");
  				out.print(sb);
  			}
  		}
  		out.flush();
  		out.close();
  
  	}
  
  
  	static class Scanner
  	{
  		StringTokenizer st;
  		BufferedReader br;
  
  		public Scanner(InputStream s){	br = new BufferedReader(new InputStreamReader(s));}
  
  		public String next() throws IOException 
  		{
  			while (st == null || !st.hasMoreTokens()) 
  				st = new StringTokenizer(br.readLine());
  			return st.nextToken();
  		}
  
  		public int nextInt() throws IOException {return Integer.parseInt(next());}
  
  		public long nextLong() throws IOException {return Long.parseLong(next());}
  
  		public String nextLine() throws IOException {return br.readLine();}
  
  		public double nextDouble() throws IOException
  		{
  			return Double.parseDouble(next());
  		}
  
  		public boolean ready() throws IOException {return br.ready();}
  
  
  	}
  }