#include<cmath>
#include<fstream>
using namespace std;

int m,n,ct,i,j,ofya[1025],d[1025][1025],a[1025],b[1025];

int main(){

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

    fin>>m>>n;

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

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

    for(i=1;i<=m;++i){

        for(j=1;j<=n;++j){

            if(a[i]==b[j]){

                d[i][j]=1+d[i-1][j-1];
            }
            else{

                d[i][j]=max(d[i-1][j],d[i][j-1]);
            }
        }
    }

    fout<<d[m][n]<<"/n";

    for(i=m;j=n;i){

        if(a[i]==b[j])
            ofya[++ct]=a[i],--i,--j;
        else if(d[i-1][j]<d[i][j-1])
            --j;
        else
            --i;
    }

    for(i=ct;i>0;--i)
        fout<<ofya[i]<<" ";
}