// https://pydefis.callicode.fr/defis/AmisEwoks/txt
#include <iostream>
#include <string>
#include <vector>
#include <set>
#include <map>
#include <limits>
using namespace std;

const int Infini = numeric_limits<int>::max();
const int N = 8; // 8-amis

map<string, set<string>> adj; // liste d'adjacences
map<int, string> intToString;
map<string, int> stringToInt;

void print()
{
	for(auto &elt: adj)
	{
		cout << elt.first << " : ";
		for(auto &ami: elt.second)
			cout << ami << ", ";
		cout << "\b\b \n";
	}
} // print()

// https://www.geeksforgeeks.org/floyd-warshall-algorithm-dp-16/
void floydWarshall(vector<vector<int>> &mat)
{
	int n = mat.size();

	for(int k = 0; k < n; k++)
		for(int i = 0; i < n; i++)
			for(int j = 0; j < n; j++)
				if(mat[i][k] != Infini && mat[k][j] != Infini &&
						mat[i][j] > mat[i][k] + mat[k][j])
					mat[i][j] = mat[i][k] + mat[k][j];
} // floydWarshall()

int main()
{
	string s, t;
	while(cin >> s >> t)
	{
		adj[s].insert(t);
		adj[t].insert(s);
	}

	int i = 0;
	for(auto &elt: adj)
	{
		intToString[i] = elt.first;
		stringToInt[elt.first] = i;
		++i;
	}

	//print();

	// matrice d'adjacences
	auto mat = vector<vector<int>>(adj.size(), vector<int>(adj.size(), Infini));
	for(size_t i = 0; i < adj.size(); i++)
		mat[i][i] = 0;
	for(auto &elt: adj)
	{
		int ind1 = stringToInt[elt.first];
		for(auto &ami: elt.second)
		{
			int ind2 = stringToInt[ami];
			mat[ind1][ind2] = mat[ind2][ind1] = 1;
		}
	}

	floydWarshall(mat);

	// couples N-amis ?
	for(size_t i = 0; i < mat.size(); i++)
		for(size_t j = i + 1; j < mat.size(); j++)
			if(mat[i][j] == N) // i et j sont N-amis
			{
				cout << intToString[i] << ", " << intToString[j] << '\n';
			}

	return 0;
} // main()