/*#include <bits/stdc++.h>
#include<fstream>
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int m,n,x,i,j,d[1025][1025],a[1025],b[1025],cnt=0,c[1025];
int main()
{
    fin>>m>>n;
    for(i=1;i<=m;i++)

    fin>>a[i];


    for(i=1;i<=n;i++)

    fin>>b[i];



    for(i=1;i<m;i++)

    for(j=1;j<n;j++)
{

if(a[i]==b[j]) d[i][j]=1+d[i-1][j-1];
else    d[i][j]=max(d[i-1][j],d[i][j-1]);}

     for(i=m,j=n;i; )

    if(a[i]==b[j]) {
    c[cnt++]=a[i];
    i--;j--;

    }
    else if (d[i-1][j]<d[i][j-1]) j--;
    else i--;



    fout<<cnt<<'\n';
    for(i=cnt-1;i>=0;i--) fout<<c[i]<<' ';





    return 0;
}
*/
#include <stdio.h>



#define maxim(a, b) ((a > b) ? a : b)

#define FOR(i, a, b) for (i = a; i <= b; ++i)

#define NMax 1024



int M, N, A[NMax], B[NMax], D[NMax][NMax], sir[NMax], bst;



int main(void)

{

    int i, j;



    freopen("cmlsc.in", "r", stdin);

    freopen("cmlsc.out", "w", stdout);



    scanf("%d %d", &M, &N);

    FOR (i, 1, M)

        scanf("%d", &A[i]);

    FOR (i, 1, N)

        scanf("%d", &B[i]);



    FOR (i, 1, M)

        FOR (j, 1, N)

            if (A[i] == B[j])

                D[i][j] = 1 + D[i-1][j-1];

            else

                D[i][j] = maxim(D[i-1][j], D[i][j-1]);



    for (i = M, j = N; i; )

        if (A[i] == B[j])

            sir[++bst] = A[i], --i, --j;

        else if (D[i-1][j] < D[i][j-1])

            --j;

        else

            --i;



    printf("%d\n", bst);

    for (i = bst; i; --i)

        printf("%d ", sir[i]);



    return 0;

}