#include <fstream>

using namespace std;
ifstream cin ("cmlsc.in");
ofstream cout ("cmlsc.out");

int n,m,i,j,a[1030],b[1030],c[1030],dp[1030][1030],k;

int main()
{
    cin>>n>>m;
    for(i=1; i<=n; i++)
        cin>>a[i];
    for(i=1; i<=m; i++)
        cin>>b[i];
    for(i=1; i<=n; i++)
        for(j=1; j<=m; j++)
        {
            if(a[i]==b[j])
                dp[i][j]=dp[i-1][j-1]+1;
            else
                dp[i][j]=max(dp[i-1][j], dp[i][j-1]);
        }
    i=n;
    j=m;
    while(i && j)
    {
        if(a[i]==b[j])
        {
            c[++k]=a[i];
            i--;
            j--;
        }
        else
        if(dp[i-1][j]>dp[i][j-1])
            i--;
        else
            j--;
    }
    cout<<k<<endl;
    for (i=k;i>=1;i--)
        cout<<c[i]<<' ';
    return 0;
}