void delete_elements(Node* head, int left, int right)
{
	Node* left_ptr = head;
	for (int i = 0; i < left; i++) {
		left_ptr = left_ptr->next;
	}
	Node* current_ptr = left_ptr->next;
	Node* next_ptr = current_ptr->next;
	for (int i = left+1; i < right; i++) {
		delete current_ptr;
		current_ptr = next_ptr;
		if (next_ptr->next) {
			next_ptr = next_ptr->next;
		}
	}
	left_ptr->next = current_ptr;
}