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

#define NMAX 1030

ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
 
int n, m, a[NMAX], b[NMAX], dp[NMAX][NMAX], rasp[NMAX], len;
 
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 = 1; i <= n; i++)
        for (j = 1; j <= m; 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]);
    i = n;
    j = m;
    while (i > 0) {
        if (a[i] == b[j]) {
            rasp[++len] = a[i];
            i--; j--;
        }
        else
            if (dp[i-1][j] < dp[i][j-1])
                j--;
            else
                i--;
    }
    fout << len << "\n";
    for (i = len; i >= 1; i--)
        fout << rasp[i] << " ";
    return 0;
}