/* The reason I gave up on this:
 * I thought I'd need to somehow track the first "node", so I wanted to
 * experiment on a more naive implementation. I don't.
 * Also, the dumb algorithm is still by far fast enough. So, Python it is. */
#include <cstdio>
#include <vector>
using namespace std;

struct CNode
{
	size_t id;
	CNode *prev = NULL, *next = NULL;
};

struct Circular
{
	vector<CNode> nodes;
	Circular(size_t size) {
		for (size_t i = 0; i < size; i++) {
			nodes.push_back(CNode{i});
		}

		// pointers to stuff in a vector? how risque!
		for (size_t i = 0; i < size - 1; i++) {
			nodes[i].next = &nodes[i+1];
			nodes[i+1].prev = &nodes[i];
		}
		CNode *f = &nodes.front();
		CNode *b = &nodes.back();
		f->prev = b;
		b->next = f;
	}

	void print() {
	}
};

int
main()
{
	int n;
	vector<int> input;
	while (scanf("%d ", &n) == 1) {
		input.push_back(n);
	}
	Circular c(input.size());
}