#include <iostream>
#include <fstream>

int n,m,a[1025],b[1025],c[1025][1025],xi,yi,x[1025];

using namespace std;

int main(){
    fstream h("cmlsc.in");

    h>>n;
    h>>m;

    for(int i=1;i<=n;i++)
        h>>a[i];
    for(int j=1;j<=m;j++)
        h>>b[j];

    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][j-1],c[i-1][j]);
        }
    }

        xi=n;yi=m;

        while(xi>1||yi>1){
            if(xi>1)while(xi>1&&c[xi][yi]==c[xi-1][yi])xi--;
            if(yi>1)while(yi>1&&c[xi][yi]==c[xi][yi-1])yi--;
            x[c[xi][yi]]=a[xi];
            if(xi>1)xi--;
            if(yi>1)yi--;

        }

        fstream write ("cmlsc.out");
        write<<c[n][m] << "\n";
        for(int i=1;i<=c[n][m];i++)
            write<<x[i]<<" ";



    h.close();
    write.close();

return 0;

}