#include <iostream>
#include <fstream>

using namespace std;

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

int M, N, A[1050], B[1050], D[1050][1050], S[1050];

int main()
{
    int k=0;
    fin>>M>>N;
    for(int i=1;i<=M;i++)
        fin>>A[i];
    for(int i=1;i<=N;i++)
        fin>>B[i];
    for(int i=1;i<=M;i++)
        for(int j=1;j<=N;j++)
            if(A[i]==B[j])
                D[i][j]=D[i-1][j-1]+1;
            else
                D[i][j]=D[i][j-1]>D[i-1][j]?D[i][j-1]:D[i-1][j];
    for (int i = M, j = N; i; )
        if (A[i] == B[j])
            S[++k] = A[i], --i, --j;
        else if (D[i-1][j] < D[i][j-1])
            --j;
        else
            --i;
    fout<<k<<"\n";
    for(int i=k;i;--i)
        fout<<S[i]<<" ";

}