#include <iostream>
#include <fstream>
using namespace std;
int n, m, a[1025], b[2015], i, j, d[1025][1025],sol[1025],k;
int main()
{
    freopen("cmlsc.in", "r", stdin);
    freopen("cmlsc.out", "w", stdout);
    scanf("%d%d", &n, &m);
    for( i = 1; i <= n; i++ )
        scanf("%d", &a[i]);
    for( j = 1; j <= m; j++ )
        scanf("%d", &b[j]);
    for( i = 1; i <= n; i++ )
        for ( j = 1; j <= m; j++ )
            if( a[i] == b[j] )
                d[i][j]++;
                else
                    d[i][j]=max(d[i-1][j], d[i][j-1]);
    i=n;
    j=m;
    while(i!=0 && j!=0)
    {
        if(a[i]==b[j])
            {sol[++k]=a[i];
            i--;
            j--;}
            else
                if(d[i-1][j]<d[i][j-1])
                    j--;
                    else
                        i--;
    }

        printf("%d\n", k);
        for(i=k; i>=1; i--)
            printf("%d ", sol[i]);

    return 0;
}