#include <fstream>
using namespace std;
#define NMax 1024
ifstream cin("cmlsc.in");
ofstream cout("cmlsc.out");
int M, N, A[NMax], B[NMax], D[NMax][NMax], sir[NMax], bst;

int main()
{
    int i, j;
    
    cin>>M>>N;
    for(i=1;i<=M;i++)
        cin>>A[i];
    for(i=1;i<=N;i++)
        cin>>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
                if(D[i-1][j]>D[i][j-1])
                    D[i][j]=D[i-1][j];
                else 
                    D[i][j]=D[i][j-1];
    for (i = M, j = N; i; )
        if (A[i] == B[j])
            {bst++;
            sir[bst] = A[i], i--, j--;}
        else if (D[i-1][j] < D[i][j-1])
            j--;
        else
            i--;

    cout<<bst<<"\n";
    for (i = bst; i>=1; i--)
        cout<<sir[i]<<" ";

    return 0;
}