#include<stdio.h>
main()
{
int a,b,c,d,count=0,e=1;
scanf("%d",&a);
int bl[a];
int num[a];

for(b=1;b<=a;b++)
{
scanf("%d",&num[b]);
bl[b]=0;
}
for(b=1;b<=a;b++)
{
  for(c=1;c<=a;c++)
 {
  if(c<=b)
  continue;
 else if(num[b]==num[c])
  bl[c]=1;
 }
}
for(b=1;b<=a;b++)
{
if(bl[b]==0)
count++;
}
int ar[count];
for(b=1;b<=a;b++)
{
	if(bl[b]==0)
	{
	ar[e]=num[b];
	e++;
	}
    
}
for(b=1;b<=count;b++)
{
 for(c=1;c<=count-b;c++)
   {
  if(ar[c]>ar[c+1])
      {
      d=ar[c+1];
      ar[c+1]=ar[c];
      ar[c]=d;
      }
   }
}
printf("%d\n",count);
for(b=1;b<=count;b++)
printf("%d ",ar[b]);
return 0;
}