#include<fstream>
#include<iostream>
using namespace std;

const int Nmax = 1024;

ifstream f("cmlsc.in");
ofstream g("cmlsc.out");

int a[Nmax],b[Nmax],c[Nmax][Nmax],d[Nmax], n, m, k = 0;
void read()
{
    f >> n >> m;
    for(int i = 1; i <= n; i ++)
        f >> a[i];
    for(int i = 1; i <= m; i ++)
        f >> b[i];
}
void solve()
{
    for(int i = 1;i <= n;i ++)
        for(int j = 1;j <= m;j ++)
            if(a[i] == b[j])
                c[i][j] = c[i-1][j-1] + 1;
            else
                c[i][j] = max(c[i-1][j],c[i][j-1]);

    g << c[n][m] << endl;

}
void print(int i,int j)
{
    while(i>0 && j>0)
        if(a[i]==b[j])
        {
            d[++k] = a[i];
            i--;
            j--;
        }
        else if(c[i-1][j] < c[i][j-1])
            j --;
        else
            i --;
    for(i = k ;i >= 1;i --)
        g<< d[i] <<" ";
}
int main()
{
    read();
    solve();
    print(n,m);
    return 0;
}