#pragma comment(linker, "/STACK:256000000")
#define _CRT_SECURE_NO_WARNINGS
#define _CRT_SECURE_NO_DEPRECATE
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<string>
#include<cstring>
#include<algorithm>
#include<cmath>
#include <set>
#include <queue>
#include <map>
#include <vector>
#include <unordered_map>
#include <assert.h>

using namespace std;

#define mp make_pair
#define pub push_back
#define con continue
#define forn(i, n) for (int i = 0; i < int(n); ++i)
#define fornr(i, n) for (int i = n - 1; i >= 0; --i)
#define forab(i, a, b) for (int i = (a); i <= int(b); ++i)
typedef long long ll;
typedef pair <int, int> pii;
typedef vector <int> vi;
typedef vector < pii > vii;
typedef vector < vector < int> > vvi;
typedef vector < vector < pair < int, int > > > vvii;

const int ZEROS = (int)(1E+2 * 4 + 100);
const int INF = (int)1E+9;

int cnt;
map <int, string> M1;
map <string, int > M2;
ll d[ZEROS][ZEROS];

void solve() {
    forn(k, cnt) {
        forn(i, cnt) {
            forn(j, cnt) {
                d[i][j] = min(d[i][j], d[i][k] + d[k][j]);
            }
        }
    }
    ll mx = -1;
    vector <pair <string, string> > ans;
    forn(i, cnt) {
        forn(j, cnt)
            if (d[i][j] > mx && d[i][j] != INF) {
                mx = d[i][j];
            }
    }
    forn(i, cnt) {
        for(int j = 0; j < i; ++j) {
            if (d[i][j] == mx) {
                string s1 = M1[i], s2 = M1[j];
                if (s1 < s2)
                    ans.pub(mp(s1, s2));
                else
                    ans.pub(mp(s2, s1));
            }
        }
    }
    sort(ans.begin(), ans.end());
    forn(i, (int)ans.size())
        cout << ans[i].first << " " << ans[i].second << endl;
}

int main() {
#ifdef  _DEBUG
    freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout);
#endif
    //ios_base::sync_with_stdio(0);
    //cin.tie(0);

    int n;
    cin >> n;
    forn(i, ZEROS) {
        forn(j, ZEROS) {
            d[i][j] = INF;
            if (i == j)
                d[i][j] = 0;
        }
    }
    forn(i, n) {
        string s1, s2;
        int x;
        cin >> s1 >> s2 >> x;
        if (!M2.count(s1)) {
            M2[s1] = cnt;
            M1[cnt] = s1;
            cnt++;
        }
        if (!M2.count(s2)) {
            M2[s2] = cnt;
            M1[cnt] = s2;
            cnt++;
        }
        d[M2[s1]][M2[s2]] = x;
        d[M2[s2]][M2[s1]] = x;
    }
    solve();
}