#include <fstream>
int n, m, i, j, s1[1025], s2[1025], d[1025][1025], lcs[1025], l;
int main()
{
    freopen("cmlsc.in", "r", stdin);
    freopen("cmlsc.out", "w", stdout);
    scanf("%d %d", &n, &m);
    for (i=1;i<=n;i++)
        scanf("%d", &s1[i]);
    for (i=1;i<=m;i++)
        scanf("%d", &s2[i]);
    for (i=n;i>0;i--)
        for (j=m;j>0;j--)
            if (s1[i]==s2[j])
                d[i][j]=d[i+1][j+1]+1;
            else
                d[i][j]=std::max(d[i+1][j], d[i][j+1]);
    i=j=1;
    while (i<=n && j<=m)
        if (s1[i]==s2[j])
        {
            lcs[++l]=s1[i];
            i++;
            j++;
        }
        else
            if (d[i+1][j]>d[i][j+1])
                i++;
            else
                j++;
    printf("%d\n", d[1][1]);
    for (i=1;i<=l;i++)
        printf("%d ", lcs[i]);
    return 0;
}