content: package v114;
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.Deque;
  import java.util.LinkedList;
  import java.util.StringTokenizer;
  
  public class ErasingAndWinning_UVa11491 {
  
  	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(), D = sc.nextInt();
  			if(N == 0)
  				break;
  			String s = sc.next();
  			Deque<Character> deque = new LinkedList<Character>();
  			for(int i = 0; i < N; ++i)
  			{
  				char c = s.charAt(i);
  				while(D > 0 && !deque.isEmpty() && deque.getLast() < c)
  				{
  					deque.removeLast();
  					--D;
  				}
  				deque.addLast(c);
  			}
  			
  			while(D-->0)	
  				deque.removeLast();
  			
  			StringBuilder sb = new StringBuilder();
  			while(!deque.isEmpty())
  				sb.append(deque.remove());
  			out.println(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();}
  	}
  }