C++ :

#include<cstdio>
int main()
{
	int a[101];
	int n,t;
	scanf("%d",&n);
	t=n;
	for(int i=1;i<=n;i++)
		scanf("%d",&a[i]);
	for(int i=1;i<=n;i++)
		for(int j=1;j<=n;j++)
			if(a[i]<a[j])
			{
				a[0]=a[i];
				a[i]=a[j];
				a[j]=a[0];
			}
	a[0]=0;
	for(int i=1;i<=n;i++)
		for(int j=1;j<=n;j++)
			if((i!=j)&&(a[i]==a[j])&&(a[i]!=0)&&(a[j]!=0)) 
				{
					t--;
					a[j]=0;	
				}
	printf("%d\n",t);
	for(int i=1;i<=n;i++)
		if(a[i]!=0) 
		{
			printf("%d",a[i]);
			t=i+1;
			break;
		}
	for(int i=t;i<=n;i++)
		if(a[i]!=0) printf(" %d",a[i]);
	return 0;
}

Pascal :

var
  n,x,i,s:integer;
  a,b:array[1..1000]of integer;
begin
	readln(n);
	for i:=1 to n do begin
		read(x);
		a[x]:=1;
	end;
	s:=0;
	for i:=1 to 1000 do s:=s+a[i];
	writeln(s);
	x:=0;
	for i:=1 to 1000 do
		if a[i]>0 then begin inc(x);b[x]:=i; end;
	for i:=1 to s-1 do write(b[i],' ');write(b[s]);
end.