#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define Max(a, b) (a) > (b) ? (a) : (b)




int main(int argc, char **argv)
{
    int a[1025], b[1025], r[1025], m, n, p = 0, i, j, aux, nr = 0;
    
    FILE *in = fopen("cmlsc.in", "r");    
    FILE *out = fopen("cmlsc.out", "w");
    
    fscanf(in, "%d %d", &m, &n);
    //printf("%d  %d\n", m , n);
    for (i = 1; i <= m; i++)
        fscanf(in, "%d", &a[i]);
    for (i = 1; i <= n; i++)
        fscanf(in, "%d", &b[i]);
        
        
    int l[m+1][n+1];
    
    for (i = 0; i <= m; i++)
        l[i][0] = 0;    
    for (j = 0; j <= n; j++)
        l[0][j] = 0;
    
    for (i = 1; i <= m; i++)    
    for (j = 1; j <= n; j++)
    {
        if(a[i] == b[j])
             l[i][j] = l[i - 1][j - 1] + 1;
        else 
             l[i][j] = Max(l[i - 1][j], l[i][j - 1]); 
        
        if (l[i][j] > nr)
        {
           r[p++] = a[i];
           nr = l[i][j];             
        }
    } 
    
    //for (i = 1; i <= m; i++)    
    //{
    //    for (j = 1; j <= n; j++)
    //        printf("%d ", l[i][j]);
    //    printf("\n");
    //}
    
    fprintf(out, "%d \n", p);
    for (i = 0; i < p; i++)
        fprintf(out, "%d ", r[i]);   
    
    fflush(stdin);
    getchar();
    
    fclose(in);
    fclose(out);
    return 0;   
}