#include <bits/stdc++.h>
using namespace std;

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

int n, m, k, a[1030], b[1030], v[1030], dp[1030][1030];

int main()
{
    int i, j;
    fin >> n >> m;
    for (i = 1 ; i <= n ; i++)
        fin >> a[i];
    for (i = 1 ; i <= m ; i++)
        fin >> b[i];
    for (i = 1; i <= n; i++)
        for (j = 1; j <= m; j++)
        {
            if (a[i] == b[j]) dp[i][j] = dp[i-1][j-1] + 1;
            else dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
        }
    fout << dp[n][m] << "\n";
    i = n; j = m;
    while (i > 0 && j > 0)
        if (a[i] == b[j])
        {
            v[++k] = a[i];
            i--; j--;
        }
        else
        {
            if (dp[i-1][j] >= dp[i][j-1]) i--;
            else j--;
        }
    for (i = k; i >= 1; i--)
        fout << v[i] << " ";
    return 0;
}