#include <iostream>
#include <fstream>
using namespace std;
ifstream in("cmlsc.in");
ofstream out("cmlsc.out");
int a[1025],b[1025],c[1025][1025],m,n,v[1025],k;
void afis(int,int);
int main()
{
    int i,j;
    in >> n >> m;

    for(i = 1; i <= n; ++i)
        in >> a[i];

    for(j = 1; j <= m; ++j)
        in >> b[j];

    for( i = 1; i <= n; ++i)
        for(j = 1; j <= m; ++j)
            if(a[i] == b[j])
                c[i][j] = c[i-1][j-1] + 1;
            else
            {
                if(c[i-1][j] >= c[i][j-1])
                    c[i][j] = c[i-1][j];
                else
                    c[i][j] = c[i][j-1];
            }
    out << c[n][m] << endl;

    afis(n,m);
   /* i = n;
    j = m;
    k = c[n][m];

    while( i && j)
    {
        if(a[i] == b[j])
        {
            v[k--] = a[i];
            i--;
            j--;
        }
        else
        {
            if( c[i-1][j] >= c[i][j-1])
                i--;
            else
                j--;
        }
    }

    for(int i = 1; i <= c[n][m]; i++)
        out << v[i] << " ";
        */
    return 0;
}
void afis(int i, int j)
{
    if( i && j)
    {
        if(a[i] == b[j])
        {
            //v[k--] = a[i];
            // i--;
            //j--;
            afis(i-1,j-1);
            out << a[i] << " ";
        }
        else
        {
            if( c[i-1][j] >= c[i][j-1])
            {
                afis(i-1,j);
            }
            else
            {
                afis(i,j-1);
            }

        }
    }
    else
        return;
}