#define DM 1025

#include <fstream>

#include <stack>

using namespace std;

 

ifstream cin ("cmlsc.in");

ofstream cout ("cmlsc.out");

int v1[DM], v2[DM], n, m, mx, mxl, dp[DM][DM], perf[DM];

stack <int> s;

 

int mxa(int a, int b)

{

    int ja = 0;

    for (int i = 1; i < b; ++i)

        if (dp[a][i] > dp[a][ja])

            ja = i;

    return ja;

}

 

int main() {

    cin >> n >> m;

    if (n >= m)

    {

        for (int i = 1; i <= n; ++i)

            cin >> v1[i];

        for (int j = 1; j <= m; ++j)

            cin >> v2[j];

    }

    else

    {

        for (int i = 1; i <= n; ++i)

            cin >> v2[i];

        for (int j = 1; j <= m; ++j)

            cin >> v1[j];

        swap(n, m);

    }

    for (int i = 1; i <= n; ++i)

    {

        mx = 0;

        for (int j = 1; j <= m; ++j)

        {

            if (v1[i] == v2[j])

                dp[i][j] = dp[i-1][mxa(i - 1, j)] + 1;

            else

                dp[i][j] = dp[i-1][j];

            if (dp[i][j] > dp[i][mx])

                mx = j;

        }

        perf[i] = mx;

        if (dp[n][mx] > dp[mxl][perf[mxl]])

            mxl = i;

    }

    s.push(v2[mx]);

    int a = mx;

    cout << dp[n][mx] << '\n';

    for (int i = mxl - 1; dp[n][mx] && i; --i)

        for (int j = a - 1; j >= 1; --j)

            if (dp[i][j] == dp[mxl][a] - 1 && v1[i] == v2[j])

            {

                s.push(v2[j]);

                a = j, --dp[n][mx], mxl = i;

                break;

            }

    while (!s.empty())

    {

        cout << s.top() << ' ';

        s.pop();

    }

    return 0;

}