#define _CRT_SECURE_NO_WARNINGS

#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <string>
#include <algorithm>
#include <cmath>
#include <ctime>
#include <vector>
#include <stack>
#include <map>
#include <set>
#include <queue>
#include <cstring>
#include <bitset>
#include <cstdio>
#include <cstdlib>
#include <cassert>

using namespace std;

typedef long long ll;
typedef double db;
typedef long double ldb;
typedef string str;

#define forn(i, n) for(int i = 0; i < n; ++i)
#define INF 1e+9
#define EPS 1e-9
#define PI 3.1415926535897932384626433832795
#define mp(a, b) make_pair(a, b)
#define pb(a) push_back(a)
#define X first
#define Y second
#define ms(x) memset(x, 0, sizeof(x))
#define ms1(x) memset(x, -1, sizeof(x))
#define sz(x) ( (int) x.size() )
#define len(x) ( (int) x.length() )
#define ALL(x) x.begin(), x.end()
#define pii pair<int, int>
#define pdd pair<double, double>
#define pll pair<ll, ll>

map<string, vector<string> > arr;

bool can(vector<string> templ) {
    vector<string> pat;
    pat.push_back("A");
    pat.push_back("B");
    pat.push_back("C");
    bool ok = true;
    forn(iter, sz(pat)) {
        int times = 0;
        int index = -1;
        forn(i, sz(templ)) {
            if (templ[i].find(pat[iter]) != -1) {
                if (index == -1) {
                    times++;
                    index = i;
                }
            }
            else {
                index = -1;
            }
        }
        if (times >= 2)
            ok = false;
    }
    return ok;
}

int main() {
#ifdef _DEBUG
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#else
    freopen("b.in", "r", stdin);
    freopen("b.out", "w", stdout);
#endif
    int n;
    cin >> n;
    forn(i, n) {
        string a, b;
        cin >> a >> b;
        arr[a].push_back(b);
    }
    vector<string> templ;
    for (map<string, vector<string> >::iterator it = arr.begin(); it != arr.end(); ++it) {
        templ.push_back((*it).X);
    }
    sort(ALL(templ));
    bool ok = false;
    do {
        ok = can(templ);
        if (ok) {
            forn(iter, sz(templ)) {
                vector<string> ans = arr[templ[iter]];
                forn(i, sz(ans)) {
                    cout << templ[iter] << " " << ans[i] << "\n";
                }
            }
            break;
        }
    } while (next_permutation(ALL(templ)));
    if (!ok) {
        cout << "Impossible\n";
    }
#ifdef _DEBUG
    cout << fixed << setprecision(15) << clock() * 1. / CLOCKS_PER_SEC;
#endif
    return 0;
}