#include <stdio.h>
#include <iostream>
#include <string.h>
int DP[1024][1024],A[1024],B[1024];
int maxim(int a,int b){
	if (a>b)
		return a;
	return b;
}
int main()
{
	freopen("cmlsc.in","r",stdin);
	freopen("cmlsc.out","w",stdout);
	int n,m;

	scanf("%d%d", &n, &m);
	for (int i=1;i<=n;++i)
		scanf("%d", &A[i]);
	for (int i=1;i<=m;++i)
		scanf("%d", &B[i]);
	DP[0][0]=0;
	for (int i=1;i<=n;i++)
		for (int j=1;j<=m;j++)
			if (A[i]==B[j])
				DP[i][j]=DP[i-1][j-1]+1;
			else
				DP[i][j]=maxim(DP[i][j-1],DP[i-1][j]);

	printf("%d\n", DP[n][m]);
	
	for (int i=1;i<=n;++i)
		for (int j=1;j<=m;++j)
			if (DP[i][j]!=DP[i-1][j-1] && A[i]==B[j])
				printf("%d ", A[i]);

	return 0;
}