#include <fstream>

using namespace std;
ifstream f("cmlsc.in");
ofstream g("cmlsc.out");
int n,m;
int a[1025],b[1025];
int dp[1025][1025];
int sub[1025];
int k;
//dp[i][j]= cmlsc formate cu primele i elemente ale subsirului A
//          si primele j elemente ale sirului B
void Citire()
{
    int i;
    f>>m>>n;
    for(i=1;i<=m;i++)
    {
        f>>a[i];
    }
    for(i=1;i<=n;i++)
    {
        f>>b[i];
    }
}

void Cmlsc()
{
    int i,j;
    for(i=1;i<=m;i++)
    for(j=1;j<=n;j++)
    {
        if(a[i]!=b[j])
        dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
        else if(a[i]==b[j]) dp[i][j]=1+dp[i-1][j-1];
    }
    g<<dp[m][n]<<"\n";

    for(i=m,j=n;i>0 && j>0;)
    {
        if(a[i]==b[j] )
        {
            sub[++k]=a[i];
            i--;j--;
        }
        else
        {
            if(dp[i-1][j]<dp[i][j-1])
            {
                    j--;
            }
            else i--;
        }
    }
    for(i=k;i>0;i--)
    g<<sub[i]<<" ";
}
int main()
{
    Citire();
    Cmlsc();
    return 0;
}