#include<stdio.h>
#define nmax 1024
#define max(a,b) ((a)>(b)?(a):(b))
int a[nmax],b[nmax],sol[nmax][nmax],solt[nmax];

int main()
{
 freopen("cmlsc.in","r",stdin);
 freopen("cmlsc.out","w",stdout);
 
 int n,m,i,j;
 scanf("%d%d",&n,&m);
 
 for(i=1; i<=n; ++i)
 scanf("%d",&a[i]);   
 
 for(i=1; i<=m; ++i)
 scanf("%d",&b[i]);
 
 for(i=1; i<=n; ++i){ 
  
   for(j=1; j<=m; ++j)
    
    if( a[i] == b[j] )
    sol[i][j]=sol[i-1][j-1]+1;
    else
    sol[i][j]=max(sol[i-1][j],sol[i][j-1]);
    
}
    printf("%d\n",sol[n][m]);
    
int aux=0;
    
 for(i=n, j=m; i&&j;){   
    if( a[i] == b[j]){
    solt[++aux]=a[i]; --i; --j; 
    }    
    else
    if(sol[i][j-1]<sol[i-1][j])
    --i;
    else
    --j;
}
    
 for(i=aux; i>=1; --i)
 printf("%d ",solt[i]);
 printf("\n");
    
    return 0;
}