// Cel mai lung sir comun.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

#include <cstdio>
constexpr auto NMAX = 1001;
int i, j, k=0;
int D[NMAX][NMAX], A[NMAX], B[NMAX], sir[NMAX];
int M, N;
int main()
{
    
    freopen("cmlsc.in", "r", stdin);
    freopen("cmlsc.out", "w", stdout);
    scanf("%d%d", &M, &N);
    for (i = 1; i <= M; i++)
        scanf("%d", &A[i]);
    for (int j = 1; j <= N; j++)
        scanf("%d", &B[j]);
    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] = (D[i - 1][j] > D[i][j - 1]) ? D[i - 1][j] : D[i][j - 1];
    for (i = M, j = N; i; )
    {
        if (A[i]==B[j])
        {
            sir[++k] = A[i];
            i--; j--;
        }
        else if (D[i - 1][j] > D[i][j-1])
            i--;
        else j--;
    }
    printf("%d \n", k);
    for (i = k; i; i--)
        printf("%d ", sir[i]);


}

// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu

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//   2. Use the Team Explorer window to connect to source control
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//   4. Use the Error List window to view errors
//   5. Go to Project > Add New Item to create new code files, or Project > Add Existing Item to add existing code files to the project
//   6. In the future, to open this project again, go to File > Open > Project and select the .sln file