#include <string.h>   
#include <stdio.h>   
#define N 1025   
int mat[N][N];   
int sir1[N];   
int sir2[N];   
int out[N];   
  
int main ()   
{FILE *f,*fout;   
 int m,n,i,j,k;   
 f=fopen("cmlsc.in","r");   
 fout=fopen("cmlsc.out","w");   
 fscanf(f,"%d%d",&n,&m);   
  
 for (i=1;i<=n;i++)   
  fscanf(f,"%d",&sir1[i]);   
  
 for (i=1;i<=m;i++)   
  fscanf(f,"%d",&sir2[i]);   
  
 memset(mat,0,sizeof(mat));   
 for (i=1;i<=n;i++)   
 {for (j=1;j<=m;j++)   
  {if(sir1[i]==sir2[j])   
   {mat[i][j]=mat[i-1][j-1]+1;}   
   else    
   {if(mat[i-1][j]>mat[i][j-1])   
     mat[i][j]=mat[i-1][j];   
    else  
     mat[i][j]=mat[i][j-1];   
   }    
  }   
 }   
    
 fprintf(fout,"%d\n",mat[n][m]);   
 for (k=0,i=n,j=m;mat[i][j]!=0;)   
 {while(mat[i][j]==mat[i-1][j])   
   i--;   
  while(mat[i][j]==mat[i][j-1])   
   j--;   
  out[k]=sir1[i];k++;   
  i--;   
  j--;   
 }   
    
 for (i=k-1;i>=0;i--)   
 {fprintf(fout,"%d ",out[i]);   
 }   
 return 0;   
}