content: package v118;
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.HashSet;
  import java.util.StringTokenizer;
  
  public class CD_UVa11849 {
  	
  	public static void main(String[] args) throws Exception 
  	{
  		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;
  			HashSet<Integer> set = new HashSet<Integer>();
  			while(N-->0)
  				set.add(sc.nextInt());
  			int ans = 0;
  			while(M-->0)
  				if(set.contains(sc.nextInt()))
  					++ans;
  			out.println(ans);
  		}
  
  		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
  		{
  			String x = next();
  			StringBuilder sb = new StringBuilder("0");
  			double res = 0, f = 1;
  			boolean dec = false, neg = false;
  			int start = 0;
  			if(x.charAt(0) == '-')
  			{
  				neg = true;
  				start++;
  			}
  			for(int i = start; i < x.length(); i++)
  				if(x.charAt(i) == '.')
  				{
  					res = Long.parseLong(sb.toString());
  					sb = new StringBuilder("0");
  					dec = true;
  				}
  				else
  				{
  					sb.append(x.charAt(i));
  					if(dec)
  						f *= 10;
  				}
  			res += Long.parseLong(sb.toString()) / f;
  			return res * (neg?-1:1);
  		}
  
  		public boolean ready() throws IOException {return br.ready();}
  
  		public boolean nextEmpty() throws IOException
  		{
  			String s = br.readLine();
  			st = new StringTokenizer(s);
  			return s.isEmpty();
  		}
  
  
  	}
  }