#include <fstream>
using namespace std;

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

int a[1025], b[1025], n, m;
int v[1025][1025], sir[1025], k;

void read()
{
    f >> n >> m;
    for(int i = 1; i <= n; ++i)
        f >> a[i];
    for(int j = 1; j <= n; ++j)
        f >> b[j];
}

void solve()
{
    for(int i = 1; i <= n; ++i)
        for(int j  = 1; j <= m; ++j)
            if(a[i] == b[j])
                v[i][j] = v[i - 1][j - 1] + 1;
            else
                v[i][j] = max(v[i][j - 1], v[i-1][j]);;

    int x = n, y = m;
    while(v[x][y])
    {
        while(v[x - 1][y] == v[x][y])
            --x;
        while(v[x][y - 1] == v[x][y])
            --y;
        sir[++k]=a[x];
        --x, --y;
    }

    g << v[n][m] << "\n";
    for(int i = k; i >= 1; --i)
        g << sir[i] << " ";
}

int main()
{
    read();
    solve();
    return 0;
}