#include <iostream>
#include <fstream>

using namespace std;

int v1[1030], v2[1030];
int n1, n2, k;
int d[1030][1030];

ifstream in("cmlsc.in");
ofstream out("cmlsc.out");

void lev()
{
    for(int i = 1; i <= n1; ++ i)
        for(int j = 1; j <= n2; ++ j)
            if(v1[i] == v2[j]) d[i][j] = d[i - 1][j - 1] + 1;
            else d[i][j] = max(max(d[i - 1][j], d[i][j - 1]), d[i - 1][j - 1]);
}

int main()
{
    in >> n1 >> n2;
    for(int i = 1; i <= n1; ++ i) in >> v1[i];
    for(int i = 1; i <= n2; ++ i) in >> v2[i];

    lev();

    k = 1;
    out << d[n1][n2] << '\n';
    for(int i = 1; i <= n1; ++ i)
        for(int j = 1; j <= n2; ++ j)
            if(d[i][j] == k)
            {
                ++ k;
                ++ i;
                if(i <= n2) out << v1[i] << " ";
            }
    return 0;
}