#include<stdio.h>
#define maxim(a,b) ((a>b)?a:b)
#define FOR(i,a,b) for(i=a;i<=b;i++)
#define p 1024
int v[p],u[p],d[p][p],sir[p],b,m,n;
int main()
{
FILE *f,*g;
f=fopen("cmlsc.in","r");
g=fopen("cmlsc.out","w");
int i,j;
fscanf(f,"%d %d",&m,&n);
FOR(i,1,m)
fscanf(f,"%d ",&v[i]);
FOR(i,1,n)
fscanf(f,"%d ",&u[i]);
FOR(i,1,m)
FOR(j,1,n)
if(v[i]==u[j])
d[i][j]=1+d[i-1][j-1];
else d[i][j]=maxim(d[i-1][j],d[i][j-1]);
for(i=m,j=n;i;)
if(v[i]==u[j])
sir[++b]=v[i],i--,j--;
else{ if(d[i-1][j]<d[i][j-1])
--j;
else --i;}
fprintf(g,"%d\n",b);
for(i=b;i>=1;--i)
fprintf(g,"%d ",sir[i]);
fcloseall();
return 0;
}