#include <stdio.h>

#define IN "cmlsc.in"
#define OUT "cmlsc.out"

#define MAXN 1025

int n,m,A[MAXN],B[MAXN];

int M[MAXN][MAXN];


FILE *f2;

void read()
{
	FILE *f=fopen(IN,"r");
	fscanf(f,"%d %d",&n,&m);
	for (int i=1;i<=n;i++)
		fscanf(f,"%d",&A[i]);

	for (int i=1;i<=m;i++)
		fscanf(f,"%d",&B[i]);
	

	fclose(f);
}

void printare(int n,int m)
{
	if (n>0 && m>0)
	{
		int maxi = 1;
		int maxx = M[n-1][m-1];
		if (M[n][m-1] > maxx)
		{
			maxx = M[n][m-1];
			maxi = 2;
		}
		if (M[n-1][m] > maxx)
		{
			maxx = M[n-1][m];
			maxi= 3;
		}

		switch(maxi)
		{
			case 2:
				printare(n,m-1);
				break;
			case 3:
				printare(n-1,m);
				break;
			default:
				printare(n-1,m-1);
				break;
		}

		if (A[n] == B[m] )
			fprintf(f2,"%d ",A[n]);
	}

	
}

void solve()
{
	f2=fopen(OUT,"w");
	
	int i,j;

	M[0][1]=M[1][0]=M[0][0]=0;
	

	for (i=1;i<=n;i++)
		for (j=1;j<=m;j++)
		{
			M[i][j] = M[i-1][j-1] + (A[i] == B[j]);
			

			if (M[i][j-1] > M[i][j])
			{
				M[i][j] = M[i][j-1];
				
			}
			if (M[i-1][j] > M[i][j])
			{
				M[i][j] = M[i-1][j];
				
			}
		}
	

	fprintf(f2,"%d\n",M[n][m]);
	printare(n,m);
	fprintf(f2,"\n");

	fclose(f2);
}

int main()
{
	read();
	solve();	
	return 0;
}