#include <fstream>

#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;

using namespace std;

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


int main(void)
{
    int i, j;

    fin>>M>>N;
    FOR (i, 1, M)
        fin>>A[i];
    FOR (i, 1, N)
        fin>>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;

    fout<<bst<<'\n';
    for (i = bst; i; --i)
        fout<<sir[i]<<' ';


    return 0;
}