#include <stdio.h>

#define maxim(a, b) ((a > b) ? a : b)

#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; i <= M; ++i)
        scanf("%d", &A[i]);
    for(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] = 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;
}