#include <stdio.h>
#define IN "cmlsc.in"
#define OUT "cmlsc.out"
#define NMAX 1030

FILE * fin=fopen(IN,"r");
FILE * fout=fopen(OUT,"w");

int a[NMAX],b[NMAX],v[NMAX];
int lcs[NMAX][NMAX];

int maxim(int,int);
int main()
{
	int n,m,i,j,nr=0;
	
	fscanf(fin,"%d%d",&n,&m);
	for(i=1;i<=n;i++)
		fscanf(fin,"%d",&a[i]);
	for(i=1;i<=m;i++)
		fscanf(fin,"%d",&b[i]);
	
	for(i=1;i<=n;i++)
		for(j=1;j<=m;j++)
		{
			if(a[i]==b[j])
				lcs[i][j]=lcs[i-1][j-1]+1;
			else
				lcs[i][j]=maxim(lcs[i][j-1],lcs[i-1][j]);
		}
	
	fprintf(fout,"%d\n",lcs[n][m]);
	
	i=n; j=m;
	while(i>0 && j>0)
	{
		if(lcs[i][j]==lcs[i-1][j-1]+1)
		{
			v[++nr]=a[i];
			i--;
			j--;
		}
		else
		{
			if(lcs[i][j-1]>lcs[i-1][j])
				j--;
			else
				i--;
		}
	}
	
	fprintf(fout,"%d",v[nr]);
	for(i=nr-1;i>=1;i--)
		fprintf(fout," %d",v[i]);
	fprintf(fout,"\n");
	
	fclose(fin);
	fclose(fout);
	return 0;
}

int maxim(int a, int b)
{
	if(a>b) return a;
	return b;
}