#include<fstream.h>   
int m,n,i,j,a[1025],b[1025],c[1025][1025],v[1025];   
ifstream f("cmlsc.in");   
ofstream g("cmlsc.out");   
int main()   
{   
int p=0;   
f>>m>>n;   
for (i=1;i<=m;i++) f>>a[i];   
for (i=1;i<=n;i++) f>>b[i];   
for (i=1;i<=m;i++)   
 for (j=1;j<=n;j++)   
  {   
   if (a[i]==b[j]) c[i][j]=1+c[i-1][j-1];   
   else  
       if (c[i][j-1]>c[i-1][j]) c[i][j]=c[i][j-1];   
       else c[i][j]=c[i-1][j];   
  }   
while (i&&j)   
 {   
  if (a[i]==b[j]) {v[p]=a[i];i--;j--;p++;}   
  else  
      if (c[i][j-1]>c[i-1][j]) j--;   
      else i--;   
 }   
g<<c[m][n]<<'\n';   
for (i=p-1;i>0;i--) g<<v[i]<<" ";   
f.close();   
g.close();   
return 0;   
}