#include<stdio.h>  
int mat[1030][1030],x[1030],z[1030],i,j,n,m,k=0;  
 
int max (int a,int b)  
{  
if (a>b)return a;  
return b;  
}  
   

int main (){  
 
FILE*f=fopen("cmlsc.in","r");  
FILE*g=fopen("cmlsc.out","w");  
 
  
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",&z[i]);  
  
   
for (i=1;i<=m;i++)  
    for (j=1;j<=n;j++)  
     {  
      if (x[j]==z[i]) mat[i][j]=mat[i-1][j-1]+1;  
         else mat[i][j]=max(mat[i-1][j],mat [i][j-1]);  
     }  
fprintf(g,"%d\n",mat[m][n]);  
for (i=1;i<=m;i++)  
     for (j=1;j<=n;j++)  
         if (mat[i][j]>k) {
                           k=mat[i][j];  
                           fprintf(g,"%d ",x[j]);  
                          }  
   
  
fclose(f);  
fclose(g);  
return 0;  
}