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

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

int a[1030] , b[1030] , n , m , 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 = n;i >= 1;i--)
        for(j = m;j >= 1;j--)
            if(a[i] == b[j]) dp[i][j] = 1 + dp[i + 1][j + 1];
            else dp[i][j] = max(dp[i + 1][j] , dp[i][j + 1]);
    fout << dp[1][1] << "\n";
    i = 1; j = 1;
    while(i <= n and 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;
}