#include <stdio.h>   
#define DIM 1025   
  
int a[DIM][DIM];   
int x[DIM];   
int y[DIM];   
int s[DIM];   
int n,m,i,j,nr;   
  
int main(){   
  FILE *f = fopen("cmlsc.in","r");   
  fscanf(f,"%d %d",&n,&m);   
  for (i=1;i<=n;i++)   
    fscanf(f,"%d",&x[i]);   
  
  for (i=1;i<=m;i++)   
    fscanf(f,"%d",&y[i]);   
  fclose(f);   
  
  for (i=1;i<=n;i++)   
    for (j=1;j<=m;j++)   
      if (x[i]==y[j])   
    a[i][j]=a[i-1][j-1]+1;   
      else  
    if (a[i-1][j]>a[i][j-1])   
      a[i][j]=a[i-1][j];   
    else  
      a[i][j]=a[i][j-1];   
  
  i=n;j=m;   
  nr=a[n][m];   
  while (nr>0)   
    if (x[i]==y[j]){   
      s[nr]=x[i];   
      nr--;   
      i--;   
      j--;   
    } else  
      if (a[i-1][j]>a[i][j-1])   
    i--;   
      else  
    j--;   
  
  FILE *g = fopen("cmlsc.out","w");   
  fprintf(g,"%d\n",a[n][m]);   
  for (i=1;i<=a[n][m];i++)   
    fprintf(g,"%d ",s[i]);   
  fclose(g);   
  
  return 0;   
}