#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int n, m, a[1025], b[1025], d[1025][1025], s[1025], k;
int main()
{
    fin >> n >> m;
    for(int i = 1; i <= n; i++)
        fin >> a[i];
    for(int i = 1; i <= m; i++)
        fin >> b[i];
    for(int i = 1; i <= n; i++)
        for(int j = 1; j <= m; j++)
            (a[i] == b[j]) ? d[i][j] = 1 + d[i - 1][j - 1] : d[i][j] = max(d[i - 1][j], d[i][j - 1]);
    int i = n, j = m;
    while(i >= 1 && j >= 1)
    {
        if(a[i] == b[j])s[++k] = a[i], i--, j--;
        else if(d[i - 1][j] < d[i][j - 1])j--;
        else i--;
    }
    fout << k << "\n";
    for(; k; k--)fout << s[k] << " ";
}