#include <stdio.h>
 
#define nmax 1024
 
inline long maxim (long a, long b)
{
	if(a>b)
		return a;
	return b;
}

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(i=1;i<=n;i++)
        scanf("%d", &b[i]);
    for(i=1;i<=m;i++)
        for(j=1;j<=n;j++)
            if (a[i]==b[j])
                d[i][j]=d[i-1][j-1]+1;
            else
                d[i][j]=maxim(d[i-1][j],d[i][j-1]);
	
	i=m,j=n;
    for(;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]);
	printf("\n");
	
    return 0;
}