#include <bits/stdc++.h>
#include<atcoder/all>
using namespace atcoder;
using namespace std;
using ll = long long;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
#define all(A) A.begin(),A.end()
#define rep(i, n) for (ll i = 0; i < (ll) (n); i++)


bool chmax(ll& p, ll q) {
    if (p < q) {
        p = q;
        return 1;
    }
    else {
        return 0;
    }
}

bool chmin(ll& p, ll q) {
    if (p > q) {
        p = q;
        return 1;
    }
    else {
        return 0;
    }
}

ll PM(ll P, ll Q) {
    if (Q == 0)return P * 10;
    ll k = 1;
    ll V = Q;
    while (V > 0) {
        V /= 10;
        k *= 10;
    }
    return P * k + Q;
}


int main() {
    
    ll N;
    cin >> N;
    if (N > 26) {
        cout << "Impossible" << endl;
        return 0;
    }
    vector<string> S(N);
    rep(i, N)cin >> S[i];

    two_sat ts(N);
    rep(i, N)rep(j, i) {
        if (S[i].substr(0, 1) == S[j].substr(0, 1)) {
            ts.add_clause(i, 1, j, 1);
        }
        if (S[i].substr(0, 1) == S[j].substr(2, 1)) {
            ts.add_clause(i, 1, j, 0);
        }
        if (S[i].substr(2, 1) == S[j].substr(0, 1)) {
            ts.add_clause(i, 0, j, 1);
        }
        if (S[i].substr(2, 1) == S[j].substr(2, 1)) {
            ts.add_clause(i,0, j, 0);
        }

        if (S[i].substr(1, 2) == S[j].substr(1, 2)) {
            ts.add_clause(i, 1, j, 1);
        }
        if (S[i].substr(1, 2) == S[j].substr(0, 2)) {
            ts.add_clause(i, 1, j, 0);
        }
        if (S[i].substr(0, 2) == S[j].substr(1, 2)) {
            ts.add_clause(i, 0, j, 1);
        }
        if (S[i].substr(0, 2) == S[j].substr(0, 2)) {
            ts.add_clause(i, 0, j, 0);
        }
    }

    bool C = ts.satisfiable();
    if(!C)cout<< "Impossible" << endl;
    else {
        auto v = ts.answer();
        rep(i, N) {
            if (v[i]) {
                cout << S[i].substr(0, 2) << " " << S[i].substr(2, 1) << endl;
            }
            else {
                cout << S[i].substr(0, 1) << " " << S[i].substr(1,2) << endl;
            }
        }
    }



}