#include <cstdio>

#define N 1025
#define max(a, b) ((a > b) ? a : b)

int m, n, a[N], b[N], c[N][N], sir[N],nr;

void citire()
{
    scanf("%d %d", &m, &n);
    for(int i=1;i<=m;i++)
        scanf("%d ", &a[i]);
    for(int i=1;i<=n;i++)
        scanf("%d ", &b[i]);
}

void prelucrare()
{
    for(int i=1;i<=m;++i)
        for(int j=1;j<=n;++j)
            if(a[i] == b[j])
                c[i][j] = 1 + c[i-1][j-1];
            else
                c[i][j] = max(c[i-1][j], c[i][j-1]);
}
void print(int i,int j)
{
    if (c[i][j] == 0)
        return;
    if (a[i] == b[j])
    {
        print (i - 1, j - 1);
        printf("%d ", a[i]);
        return;
    }
    if (c[i - 1][j] > c[i][j - 1])
        print (i - 1, j);
    else
        print (i, j - 1);
}
int main()
{
    freopen("cmlsc.in","r",stdin);
    freopen("cmlsc.out","w",stdout);
    citire();
    prelucrare();
    printf("%d\n",c[m][n]);
    print(m,n);
    return 0;
}