#include <stdio.h>
using namespace std;
FILE * fin=fopen("cmlsc.in","r");
FILE * fout=fopen("cmlsc.out","w");
int x[1200],y[1200];
int mat[1200][1200];
 int h=0,st[5000],k,i1,j1;
inline int max(int i,int j)
{
    if(mat[i-1][j]>mat[i][j-1]) return mat[i-1][j];
    return mat[i][j-1];
}
int main()
{
    int l1,l2;
    fscanf(fin,"%d%d",&l1,&l2);
    int i;
    for(i=1;i<=l1;i++) fscanf(fin,"%d",&x[i]);
    for(i=1;i<=l2;i++) fscanf(fin,"%d",&y[i]);

    int j;
    for(i=1;i<=l1;i++){
        for(j=1;j<=l2;j++){
            if(x[i]==y[j]) mat[i][j]=mat[i-1][j-1]+1;
            else mat[i][j]=max(i,j);

        }
    }


    /*fprintf(fout,"  ");
    for(j=1;j<=l2;j++) fprintf(fout,"%d ",y[j]);
    fprintf(fout,"\n");
    for(i=1;i<=l1;i++){
        fprintf(fout,"%d ",x[i]);
        for(j=1;j<=l2;j++){
            fprintf(fout,"%d ",mat[i][j]);}
            fprintf(fout,"\n");}

*/
    i=l1;j=l2;
    int ok=1;
    while(ok){
       if(x[i]==y[j]){
       h++;
       st[h]=x[i];
       }

       if(x[i-1]==y[j-1]){ i--;j--; }
       else if(x[i-1]==y[j]) i--;
            else if(x[i]==y[j-1]) j--;
                else {
                k=mat[i-1][j-1];i1=i-1;j1=j-1;
                if(mat[i-1][j]>k) {k=mat[i-1][j]; i1=i-1; j1=j;}
                if(mat[i][j-1]>k) {k=mat[i][j-1]; i1=i; j1=j-1;  }
                i=i1;j=j1;
                }

        if(i<=0 || j<=0) ok=0;
    }
    fprintf(fout,"%d\n",h);
    for(i=h;i>=1;i--){
        fprintf(fout,"%d ",st[i]);
    }




    return 0;

}