#include <iostream>
#include <fstream>
using namespace std;
ifstream in("cmlsc.in");
ofstream out("cmlsc.out");
int a[1024],b[1024],c[1024][1024];
void drum(int i,int j)
{if(i==0||j==0)
return;
if(a[j]==b[i])
{drum(i-1,j-1);
out<<a[j]<<" ";

}
else
{if(a[j-1]==b[i])
drum(i,j-1);
else
drum(i-1,j);

}

}

int main()
{

    int n,m,i,j;
    in>>n>>m;
    for(i=1; i<=n; i++)
        in>>a[i];
    for(i=1; i<=m; i++)
        in>>b[i];


 for(i=1;i<=m;i++)
 {for(j=1;j<=n;j++)
 {if(a[j]==b[i])
   c[i][j]=c[i-1][j-1]+1;
   else
   c[i][j]=max(c[i-1][j],c[i][j-1]);
 }}
  out<<c[m][n]<<endl;
  drum(m,n);

    return 0;
}