boj_1764.java

package sorting;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.StringTokenizer;

public class boj_1764 {
    public static void main(String[] args) throws IOException {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st=new StringTokenizer(br.readLine());
        int N=Integer.parseInt(st.nextToken());
        int M=Integer.parseInt(st.nextToken());

        HashSet<String> set=new HashSet<>();

        for(int i=0;i<N;i++){
            set.add(br.readLine());
        }

        ArrayList<String> res=new ArrayList<>();
        for(int i=0;i<M;i++){
            String s=br.readLine();
            if(set.contains(s)){
                res.add(s);
            }
        }
        Collections.sort(res);
        System.out.println(res.size());
        for(String s: res){
            System.out.println(s);
        }
    }
}