package string;

import java.io.*;

import java.util.*;

class Bj1764 {

public static void main(String[] args) throws IOException {

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

StringTokenizer st = new StringTokenizer(br.readLine());

int N = Integer.parseInt(st.nextToken());

int M = Integer.parseInt(st.nextToken());

Set<String> dj = new HashSet<>();

for (int i = 0; i < N; i++) {

dj.add(br.readLine());

}

List<String> dbj = new ArrayList<>();

for (int i = 0; i < M; i++) {

String name = br.readLine();

if (dj.contains(name)) {

dbj.add(name);

}

}

Collections.sort(dbj);

bw.write(dbj.size() + "\n");

for (String name : dbj) {

bw.write(name + "\n");

}

bw.flush();

br.close();

bw.close();

}

}