#include <cstdio>
#include <iostream>

using namespace std;
FILE *f,*g;
int a[1050],b[1050],d[1050][1050];

void tipar(int m, int n)
{
    if(d[m][n])
    {
        if(a[m]==b[n])
        {
            tipar(m-1,n-1);
            fprintf(g,"%d ",a[m]);
        }
        else
            if(d[m-1][n]>d[m][n-1])
                tipar(m-1,n);
            else
                tipar(m,n-1);
    }
}
void dinamica(int m,int n)
{
    for(int i=1;i<=m;++i)
        for(int j=1;j<=n;++j)
            if(a[i]==b[j])
                d[i][j]=d[i-1][j-1]+1;
            else
                d[i][j]=max(d[i-1][j],d[i][j-1]);
}
int main()
{    int m,n;
    f=fopen("cmlsc.in","r");
    g=fopen("cmlsc.out","w");
    fscanf(f,"%d %d",&m,&n);
    for(int i=1;i<=m;++i)
        fscanf(f,"%d",&a[i]);
    for(int i=1;i<=n;++i)
        fscanf(f,"%d",&b[i]);
    dinamica(m,n);
  /*  for(int i=1;i<=m;++i)
    {
        for(int j=1;j<=n;++j)
            fprintf(g,"%d",d[i][j]);
        fprintf(g,"\n");
    }*/
    fprintf(g,"%d\n",d[m][n]);
    tipar(m,n);

    fclose(f);
    fclose(g);
    return 0;
}