#include<stdio.h>

const int k=1024;
int n,m,a[k],b[k],x[k][k],s[k],l;

void citire()
{
 int i;
 FILE*f=fopen("cmlsc.in","r");
 fscanf(f,"%d %d",&m,&n);
 for(i=1;i<=m;i++)
	fscanf(f,"%d",&a[i]);
 for(i=1;i<=n;i++)
	fscanf(f,"%d",&b[i]);
 fclose(f);
}

void rezolv ()
 { int i,j;
   for(i=1;i<=m;i++)
    for(j=1;j<=n;j++)
      if(a[i]==b[j]) x[i][j]=x[i-1][j-1]+1;
        else { x[i][j]=x[i][j-1];
  	       if (x[i-1][j]>x[i][j-1]) x[i][j]=x[i-1][j]; }
   i=m;
   j=n;
   while(i&&j)
	if(a[i]==b[j]){ s[++l]=a[i];
			i--;
			j--;}
	else if(x[i][j-1]>x[i-1][j]) j--;
	     else i--;

   }
int main()
{int i;
 FILE*g=fopen("cmlsc.out","w");
 citire();
 rezolv();
 fprintf(g,"%d\n",l);
 for(i=l;i>=1;i--)
	fprintf(g,"%d ",s[i]);
 fclose(g);
 return 0;
}