#include <fstream>
#define DMAX 1030
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int a[DMAX],b[DMAX],m,n;
int lgmax[DMAX][DMAX];
int unde [DMAX][DMAX];
int main()
{   int i,j;
    fin>>n;fin>>m;
for(i=1;i<=n;i++)fin>>a[i];

for(i=1;i<=m;i++)fin>>b[i];

for(i=n;i>0;i--)
    for(j=m;j>0;j--)
    {if(a[i]==b[j])
        {
            lgmax[i][j]=1+lgmax[i+1][j+1];
            unde[i][j]=1;
        }
        else
            if(lgmax[i+1][j]>lgmax[i][j+1])
        {
            lgmax[i][j]=lgmax[i+1][j];unde[i][j]=2;
        }
        else
        {
             lgmax[i][j]=lgmax[i][j+1];unde[i][j]=3;
        }

    }
fout<<lgmax[1][1]<<'\n';
i=1;j=1;
while(i<=n&&j<=m)
{
    if(unde[i][j]==1)
    {fout<<a[i]<<' ';i++;j++;}
    else
        if(unde[i][j]==2)
        i++;
    else
        j++;

}

    return 0;
}