#include <iostream>
#include <fstream>
#include <string>
#include <algorithm>
#include <cctype>
#include <stdio.h>

#define SIZE 1025

using namespace std;

int A[SIZE];
int B[SIZE];
int RES[SIZE];

int SUB[SIZE][SIZE];

int main()
{
    freopen("cmlsc.in", "r", stdin);
    freopen("cmlsc.out", "w", stdout);
    int M, N;
    scanf("%d %d", &M, &N);
    for(int i = 0; i < SIZE; i++) {A[i] = 0; B[i] = 0; RES[i] = 0;}
    for(int i = 1; i < M + 1; i++) scanf("%d", &(A[i]));
    for(int i = 1; i < N + 1; i++) scanf("%d", &(B[i]));

    for(int i = 0; i < SIZE; i++) {SUB[i][0] = 0; SUB[0][i] = 0;}

    for(int s = 2; s <= M + N; ++s)
    for(int i = max(1, s - N); (i <= M ) || (s - i >= 1); ++i)
    {
        SUB[i][s-i] = max(max(SUB[i-1][s-i], SUB[i][s-i-1]), ((A[i] == B[s-i]) + SUB[i-1][s-i-1]));
    }
    int i = M, j = N;
    int c = SUB[M][N];

    while(c > 0)
    {
        if (SUB[i][j-1] == SUB[i-1][j])
        {
            if (SUB[i][j] == SUB[i-1][j])
                --i;
            else {
                RES[c] = A[i];
                --i;
                --j;
                --c;
                }
        } else  if (SUB[i][j] == SUB[i-1][j])
                    --i;
                else --j;
    }

    printf("%d\n", SUB[M][N]);
    printf("%d", RES[1]);
    for (int i = 2; i <= SUB[M][N]; ++i)
        printf(" %d", RES[i]);
    //printf("\n");

/*
    for(int i = 0; i < M; i++) printf("%d ", A[i]);
    printf("\n");
    for(int i = 0; i < N; i++) printf("%d ", B[i]);
    printf("\n");
*/


    return 0;
}