#include <bits/stdc++.h>

using namespace std;

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

int dp[1030][1030]; /// dp[i][j] = lungimea max a unui subsir obtinut din a[i..n]
                    ///            si b[j...m]
int n, m;
int a[1030], b[1030];

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