#include <iostream>
#include <fstream>
using namespace std;
ifstream f("cmlsc.in");
ofstream g("cmlsc.out");
#define MAXN 1030
int n,m,v[MAXN],w[MAXN],a[MAXN][MAXN],sir[MAXN],nr;
void drum(int x,int y)
{
    if(x>0&&y>0)
    {if(v[x]==w[y])
    {
        sir[++nr]=v[x];
        drum(x-1,y-1);
    }
    else
    if(a[x-1][y]>a[x][y-1])
    drum(x-1,y);
    else
    drum(x,y-1);
    }
}
int main()
{
    f>>n>>m;
    for(int i=1;i<=n;i++)
    f>>v[i];
    for(int i=1;i<=m;i++)
    f>>w[i];
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=m;j++)
        {
            if(v[i]==w[j])
            a[i][j]=a[i-1][j-1]+1;
            else
            a[i][j]=max(a[i-1][j],a[i][j-1]);
        }
    }
    drum(n,m);
    g<<a[n][m]<<'\n';
    for(int i=a[n][m];i>=1;i--)
    g<<sir[i]<<' ';

    return 0;
}