#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[ 1024], b[ 1024], 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, m)
            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;
}