#include <bits/stdc++.h>
#define DMAX 1032

using namespace std;

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

int n, m, a[DMAX], b[DMAX], LCS[DMAX][DMAX];
char unde[DMAX][DMAX];

void citire();
void pd();
void afisare();

int main()
{
    citire();
    pd();
    afisare();
    return 0;
}

void citire()
{
    fin>>n>>m;
    for( int i=1; i<=n; i++)
        fin>>a[i];
    for( int i=1; i<=m; i++)
        fin>>b[i];
}
void pd()
{
    int i,j;
    for(i=n; i>0; i--)
        for(j=m; j>0; j--)
        {
            if(a[i]==b[j])
            {
                LCS[i][j]=1+LCS[i+1][j+1];
                unde[i][j]='1';
            }
            else if(LCS[i+1][j]>LCS[i][j+1])
            {
                LCS[i][j]=LCS[i+1][j];
                unde[i][j]='2';
            }
            else
            {
                LCS[i][j]=LCS[i][j+1];
                unde[i][j]='3';
            }

        }
}
void afisare()
{
    int i,j;
    fout<<LCS[1][1]<<'\n';
    i=1;
    j=1;
    while(i<=n && j<=m)
    {
        if(unde[i][j]=='1')
        {
            fout<<a[i]<<' ';
            i++;
            j++;
        }
        else if (unde[i][j]=='2')
            i++;
        else
            j++;
    }
    fout<<'\n';
    fout.close();
}