#include <iostream>
#include <fstream>
using namespace std;
ifstream f("cmlsc.in");
ofstream g("cmlsc.out");

int a[1025],b[1025],n,m;
int v[1025][1025],sir[1025],k;

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];

}

int main()
{
    read();
    for(int i=1;i<=n;++i)
        for(int j=1;j<=m;++j)
        {
            if(a[i]==b[j])
                v[i][j]=v[i-1][j-1]+1;
            else
                v[i][j]=max(v[i][j-1],v[i-1][j]);
        }
    int x=n,y=m;
    while(v[x][y])
    {
        while(v[x-1][y]==v[x][y])
            --x;
        while(v[x][y-1]==v[x][y])
            --y;
        sir[++k]=a[x];
        --x,--y;
    }
    g<<v[n][m]<<"\n";
    for(int i=k;i>=1;--i)
        g<<sir[i]<<" ";
    return 0;
}