#include <stdio.h>



#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;



int main(void)

{

    int i, j;



    freopen("cmlsc.in", "r", stdin);

    freopen("cmlsc.out", "w", stdout);



    scanf("%d %d", &M, &N);

    FOR (i, 1, M)

        scanf("%d", &A[i]);

    FOR (i, 1, N)

        scanf("%d", &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;



    printf("%d\n", bst);

    for (i = bst; i; --i)

        printf("%d ", sir[i]);



    return 0;

}