#include <fstream>

using namespace std;

const char InFile[]="cmlsc.in";

const char OutFile[]="cmlsc.out";

const int Max=1024;

 int MAX2(int a, int b){

if(a>b){return a;}else{return b;}

}
 
int m,n,a[Max],b[Max],d[Max][Max],sir[Max],len;

 int main(void)

{

ifstream fin(InFile);

fin>>m>>n;

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

fin>>a[i];

}

for(register int i=1;i<=n;++i){

fin>>b[i];

}

fin.close();
 
for(register int i=1;i<=m;++i){

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

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

d[i][j]=1+d[i-1][j-1];

}else{

d[i][j]=MAX2(d[i-1][j],d[i][j-1]);

}

}

}

 

for(register int i=m,j=n;i>0;){

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

sir[++len]=a[i];

--i;

--j;

}else if (d[i-1][j]<d[i][j-1]){

--j;

}else{

--i;

}

}

 

ofstream fout(OutFile);

fout<<len<<"\n";

for(register int i=len;i>0;--i){

fout<<sir[i]<<" ";

}

fout.close();

return 0;

}