#include <stdio.h>
#define max(a,b) ((a > b) ? (a) : (b))
int a[1025], b[1025], d[1025][1025], n, m, sir[1025], k=0;
int main()
{ 
	int i, j;
	freopen("cmlsc.in", "r", stdin);
    freopen("cmlsc.out", "w", stdout);
	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]);
    for (int i=1; i<=m; i++)
		for (int j=1; j<=n; j++)
			if (a[i] == b[j])
				d[i][j] = 1 + d[i-1][j-1];
			else
				d[i][j] = max(d[i-1][j],d[i][j-1]);
    for (i = m, j = n; i; )
		if (a[i] == b[j])
			sir[++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; --i)
		printf("%d ", sir[i]);
return 0;
}