#include <vector>
#include <fstream>
#include <cstdlib>
#include <iterator>
#include <algorithm>
#define N_MAX 1033

using namespace std;
int C[N_MAX][N_MAX], v[2][N_MAX];
vector< int > r;
inline int _max( int x, int y ) { return ( x >= y ? x : y ); };
int main( void )
{
	int i, j;
	ifstream in( "cmlsc.in" );
	in>>v[0][0]>>v[1][0];
	for( i=1; i <= v[0][0]; ++i )
		in>>v[0][i];
	for( j=1; j <= v[1][0]; ++j )
		in>>v[1][j];
	for( i=1; i <= v[0][0]; ++i )
		for( j=1; j <= v[1][0]; ++j )
			if( v[0][i] == v[1][j] )
				C[i][j]=1+C[i-1][j-1];
			else C[i][j]=_max( C[i-1][j], C[i][j-1] );
	for( i=v[0][0], j=v[1][0]; i && j; )
		if( v[0][i] == v[1][j] )
			r.push_back( v[0][i] ), --i, --j;
		else if( C[i-1][j] >= C[i][j-1] )
				--i;
			 else --j;
	ofstream out( "cmlsc.out" );
	out<<r.size()<<'\n';
	copy( r.rbegin(), r.rend(), ostream_iterator<int>( out, " " ) );
	out<<'\n';
	return EXIT_SUCCESS;
}