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

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

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

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++)
            if (a[i] != b[j]) dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
            else dp[i][j] = dp[i - 1][j - 1] + 1;
    fout << dp[n][m] << "\n";
    int i = n, j = m;
    while (i > 0 && j > 0)
    {
        if (a[i] == b[j])
        {
            sol[++k] = a[i];
            i--; j--;
        }
        else if (dp[i - 1][j] > dp[i][j - 1])
            i--;
        else j--;
    }
    for (i = dp[n][m]; i > 0; i--)
        fout << sol[i] << " ";
    fout << "\n";
    fin.close();
    fout.close();
    return 0;
}
/**
1 7 3 9 5 8 5
7 8 5

  7 8 5
1 0 0 0
7 1 1 1
3 1 1 1
9 1 1 1
5 1 1 2
8 1 2 2
5 1 2 3

*/