#include <iostream>
#include <string>
using namespace std;

const int MAXV = 200;
const int REMOVED = 2;

char adj[MAXV][MAXV];

string names[MAXV];
int nv;
int nRem;

int getVnum(string s)
{
	for(int i=0; i<nv; i++) {
		if (names[i] == s)
			return i;
	}
	names[nv++] = s;
	return nv-1;
}

void removeEdges(int v, int *path, int len)
{
	bool isSink = true;
	for(int i=0; i<nv; i++) {
		if (adj[v][i] == 1) {
			isSink = false;
			path[len] = i;
			removeEdges(i, path, len+1);
		}
	}
	if (isSink) {
		for(int i=0; i<len-2; i++) {
			for(int j=i+2; j<len; j++) {
				if (adj[path[i]][path[j]] == 1) {
					nRem++;
					adj[path[i]][path[j]] = REMOVED;
				}
			}
		}
	}
}

void sort(int *index)
{
	index[0] = 0;
	for(int i=1; i<nv; i++) {
		int j=i;
		while (j > 0 && names[index[j-1]] > names[i]) {
			index[j] = index[j-1];
			j--;
		}
		index[j] = i;
	}
}

int main()
{
	int n, icase=0;
	int path[MAXV];
	int index[MAXV];
	cin >> n;
	while (n > 0) {
		icase++;
		for(int i=0; i<MAXV; i++)
			for(int j=0; j<MAXV; j++)
				adj[i][j] = 0;
		nv = 0;
		for(int i=0; i<n; i++) {
			string s1, s2;
			cin >> s1 >> s2;
			int v1 = getVnum(s1);
			int v2 = getVnum(s2);
			adj[v1][v2] = 1;
		}
		nRem = 0;
		for(int i=0; i<nv; i++) {
			path[0] = i;
			removeEdges(i, path, 1);
		}
		sort(index);
		cout << "Case " << icase << ": " << nRem;
		for(int i=0; i<nv; i++)
			for(int j=0; j<nv; j++)
				if (adj[index[i]][index[j]] == REMOVED)
					cout << ' ' << names[index[i]] << ',' << names[index[j]];
		cout << endl;

		cin >> n;
	}
}