A natural number `N` is read, followed by `N` integer values. Build a **singly linked list** containing the values in **reading order** (the first value is the head, the last is the tail). Reverse the list **by modifying the links** (without copying values into an auxiliary array). After reversing, traverse the list and print the values separated by single spaces. Use a structure `Node { int val; Node* next; }` with `new` for allocation. Do not use STL containers.