#include <stdio.h>
#define maxn 1026

int n,m,i,j,q;
int a[maxn],b[maxn],d[maxn][maxn],sol[maxn];

int max(int a,int b)
{
    if(a>b)
        return a;
    return b;
}

int main()
{
    FILE *f1,*f2;
    f1=fopen("cmlsc.in","r");
    f2=fopen("cmlsc.out","w");

    fscanf(f1,"%d%d",&n,&m);
    for(i=1;i<=n;i++)
        fscanf(f1,"%d",&a[i]);
    for(i=1;i<=m;i++)
        fscanf(f1,"%d",&b[i]);

    for(i=1;i<=n;i++)
    {
        for(j=1;j<=m;j++)
            if(a[i]==b[j])
                d[i][j]=d[i-1][j-1]+1;
            else
                d[i][j]=max(d[i-1][j],d[i][j-1]);
    }


    i=n;j=m;
    while(i && j)
        if(a[i]==b[j])
        {
            sol[++q]=a[i];
            i--;j--;
        }
        else if(d[i-1][j]>d[i][j-1])
            i--;
        else j--;


    fprintf(f2,"%d\n",q);
    while(q)
        fprintf(f2,"%d ",sol[q--]);


    return 0;
}