#include <iostream>
#include <fstream>

using namespace std;

ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");

int n,m,a[1030],b[1030],v[1030][1030],rez[1030],cnt=0;

void cmlsc(int a[], int n, int b[], int m)
{
    for(int i=1; i<=n; i++)
    {
        for(int j=1; j<=m; j++)
        {
            if(a[i]==b[j])
                v[i][j]=v[i-1][j-1]+1;
            else
                v[i][j]=max(v[i][j-1],v[i-1][j]);
        }
    }
    fout<<v[n][m]<<"\n";
    int i=n,j=m;
    while(v[i][j]!=0)
    {
        if(a[i]==b[j])
        {
            rez[++cnt]=a[i];
            i--;
            j--;
        }
        else if(v[i][j-1]<v[i-1][j])
            i--;
        else j--;

    }


    for(int i=cnt; i>=1; i--)
        fout<<rez[i]<<" ";
}
int main()
{
    fin>>n>>m;
    for(int i=1; i<=n; i++)
    {
        fin>>a[i];
    }
    for(int i=1; i<=m; i++)
    {
        fin>>b[i];
    }
    cmlsc(a,n,b,m);
    return 0;
}