#include <bits/stdc++.h>
#define nmax 1025

using namespace std;

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

int m,n,i,j,a[nmax],b[nmax],v[nmax][nmax],sir[nmax],c;

void Read()
{
    f>>n>>m;
    for(i=1; i<=n; i++)
        f>>a[i];
    for(i=1; i<=m; i++)
        f>>b[i];

    for(i=1; i<=n; i++)
        for(j=1; j<=m; j++)
            if(a[i]==b[j])
                v[i][j]=v[i-1][j-1]+1;
            else if(v[i-1][j]>v[i][j-1])
                v[i][j]=v[i-1][j];
            else
                v[i][j]=v[i][j-1];

    i=n;
    j=m;
    while(i>0)
        if(a[i]==b[j])
        {

            sir[c]=a[i];
            c++;
            i--;
            j--;
        }
        else if(v[i-1][j]>v[i][j-1])
            i--;
        else
            j--;
    g<<v[n][m]<<endl;
    for(i=c-1; i>=0; i--)
        g<<sir[i]<<' ';
}

int main()
{
    Read();
    return 0;
}