var b,c,f,n,g:longint;
a:array[1..1000] of boolean;
d:integer;
begin
readln(n);
b:=0;
fillchar(a,sizeof(a),false);
for f:=1 to n do
begin
read(c);
if not a[c] then begin a[c]:=true;inc(b);end;
end;
writeln(b);
for f:=1 to 1000 do
if a[f] then write(f,' ');
readln
end.{qqqqqqq}
int main()
{
int n=0,i=0,m=0,j=0,aa=0;
int a[100];
while(scanf("%d",&n)==1)
{
m=n;
for(i=0;i<n;i++)
{
scanf("%d",&a[i]);
for(j=0;j<i;j++)
{
if(a[i]==a[j])
{
a[i]=0;
m--;
break;
}
if(a[i]<a[j])
{
aa=a[i];
a[i]=a[j];
a[j]=aa;
}
}
}
printf("%d\n",m);
for(i=0;i<n;i++)
{
if(a[i]>0) printf("%d ",a[i]);
}
printf("\n");
}
return 0;
}