[백준] 1764번 듣보잡

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
		Scanner kb = new Scanner(System.in);
		
		int N = kb.nextInt();
		int M = kb.nextInt();
		kb.nextLine();
		
		HashSet<String> set = new HashSet<>();
		
		for(int i=0; i<N; i++) {
			set.add(kb.nextLine());
		}
		
		ArrayList<String> answer = new ArrayList<>();
		
		for(int i=0; i<M; i++) {
			String name = kb.nextLine();
			
			if(set.contains(name)) {
				answer.add(name);
			}
		}
		
		Collections.sort(answer);
		
		System.out.println(answer.size());
		
		for(String name: answer) {
			System.out.println(name);
		}
		
	}
	
	
}