#include<fstream>
#define DMAX 1032

using namespace std;

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

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

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

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(){
    for(int i=n; i>0; i--){
        for(int 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(){
    fout << LCS[1][1] << '\n';
    int i=1;
    int 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';
}