/*

#include <iostream>
#include <fstream>
#include <vector>

using namespace std;

const int MAX = 1026;

int N , M;

vector <vector <  vector <int>  > > LCS ;
vector <int>  sir1 , sir2;

void findLCS(){

    int i,j,x;


    for ( i = 1; i <= N ; i++)
        for ( j = 1 ;j <= M ;j++)
            if ( sir1 [i] == sir2 [j]){
                for ( x = 0 ; x < LCS [ i - 1] [ j - 1].size() ; x++)
                    LCS [ i ] [ j ].push_back(LCS [ i - 1] [ j - 1] [ x ]);
                    LCS [ i ] [ j ].push_back ( sir1 [ i ] );
            }

            else{
                if ( LCS [ i ] [ j - 1 ].size() > LCS [ i-1 ] [ j ].size() )
                  for ( x = 0 ; x < LCS [ i] [ j -1 ].size() ; x++){
                        LCS [ i ] [ j ].push_back(LCS [ i ] [ j-1 ] [ x ]);
                    }
                else
                  for ( x = 0 ; x < LCS [ i - 1 ] [ j ].size() ; x++){
                        LCS [ i ] [ j ].push_back(LCS [ i -1 ] [ j ] [ x ]);
                    }
            }


}

int main()
{
    ifstream f("cmlsc.in", ios::in);
    ofstream g("cmlsc.out", ios::out);
    f>>N>>M;


    LCS.resize(MAX);

    for ( int i = 0 ; i < MAX ; i++)
        LCS [ i ].resize(MAX);

    sir1.resize(0);
    sir2.resize(0);

    sir1.push_back(0);
    sir2.push_back(0);

    int cpyN = N , cpyM = M ,x;

    while (cpyN--){
        f>>x;
        sir1.push_back(x);
    }
    while (cpyM--){
        f>>x;              //
        sir2.push_back(x);
    }


    findLCS();

    g<<LCS[ N ] [ M ].size()<<"\n";
        for ( int i = 0 ; i < LCS[ N ] [ M ].size() ; i++)
            g<<LCS[ N ] [ M ] [ i ]<<" ";
    return 0;
}
*/


#include <iostream>
#include <fstream>
#include <vector>

using namespace std;

ifstream f("cmlsc.in", ios::in);
ofstream g("cmlsc.out", ios::out);

const int MAX = 1026;

int N , M , LCS [ MAX ] [ MAX ];

vector <int>  sir1 , sir2, sol;

int myMax ( int i , int j ){

    if(i>j) return i;
    return j;

}

void findLCS(){

    unsigned  int i , j ;
    for ( i = 1 ; i <= N ; i++ )
        for ( j = 1 ;j <= M ; j++){
            if (sir1 [ i ] == sir2 [ j ] )
                LCS [ i ] [ j ] = LCS [ i-1 ] [ j-1 ] + 1;
            else
                LCS [ i ] [ j ] = myMax ( LCS [ i-1 ] [ j ], LCS [ i ] [ j-1 ] );
        }

    i = N ; j = M;

    while ( i > 0 && j > 0 ){
        if ( sir1  [ i ] == sir2 [ j ] ){
            sol.push_back( sir1 [ i ] );
            i--;j--;
        }
        else{

            if ( LCS [ i-1 ] [ j ] > LCS [ i ] [ j-1 ] )
                i--;
            else
                j--;
        }

    }

    g<<LCS[N][M]<<"\n";

    for ( int i = sol.size() - 1  ; i >= 0 ;i--)
        g<<sol [ i ]<<" ";



}

int main(){


    f>>N>>M;

    sir1.resize(0);
    sir2.resize(0);

    sir1.push_back(0);
    sir2.push_back(0);

    int cpyN = N , cpyM = M ,x;

    while (cpyN--){
        f>>x;
        sir1.push_back(x);
    }
    while (cpyM--){
        f>>x;              //
        sir2.push_back(x);
    }

    findLCS();


}