#include <fstream>
#include <queue>
using namespace std;

ifstream f("componenteconexe.in");
ofstream of("componenteconexe.out");

int n, viz[101], viz1[101];
bool a[101][101];
queue <int> coada;
priority_queue <int, vector<int>, greater<int>> coada1;

void dfs1(int nod) {
	//of << nod << " ";
	viz1[nod] = 1;

	for (int i = 1; i <= n; i++)
		if (a[nod][i] && !viz1[i]) dfs1(i);
}

void bfs(int nod) {
	viz[nod] = 1;
	coada.push(nod);

	while (!coada.empty()) {
		for (int i = 1; i <= n; i++) {
			if (a[coada.front()][i] && !viz[i])
				viz[i] = 1, coada.push(i);
		}
		coada1.push(coada.front());
		coada.pop();
	}
}

int main() {
	int c, b, i, cnt = 0;
	f >> n;

	if (n == 1) {
		of << 1 << endl;
		of << 1;
		return 0;
	}

	for (i = 0; i < n; i++) {
		f >> c >> b;
		a[c][b] = true;
		a[b][c] = true;
	}

	for (i = 1; i <= n; i++)
		if (!viz1[i]) cnt++, dfs1(i);

	of << cnt << endl;
	for (i = 1; i <= n; i++)
		if (!viz[i]) {
			 bfs(i);
			 while (!coada1.empty())
				 of << coada1.top() << " ", coada1.pop();
			of << endl;
		}

	return 0;
}