/**
* Reads in a sequence of pairs of integers (between 0 and N-1) from standard input, where each
* integer represents some object; if the objects are in different components, merge the two
* components and print the pair to standard output.
*/
public static void main(String[] args) {
int N = StdIn.readInt();
QuickUnionUF uf = new QuickUnionUF(N);
while (!StdIn.isEmpty()) {
int p = StdIn.readInt();
int q = StdIn.readInt();
if (uf.connected(p, q)) continue;
uf.union(p, q);
StdOut.println(p + " " + q);
}
StdOut.println(uf.count() + " components");
}
