1 Ptr Reverse(Ptr head int k)
 2 {
 3   cnt=1;
 4   new=head->new;
 5   old=new->old;
 6   while(cnt<k)
 7   {
 8     tmp=old->tmp;
 9     old->next=new;
10     new=old;
11     old=tmp;
12     cnt++;
13    }
14    head->next->next=old;
15    return new;
16 }