#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <tuple>
#include <deque>
#include <array>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
#include <fstream>
#include <complex>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
using namespace std;

using ll = long long;
constexpr int INF = 1001001001;
// constexpr int mod = 1000000007;
constexpr int mod = 998244353;

template<class T>
inline bool chmax(T& x, T y){
    if(x < y){
        x = y;
        return true;
    }
    return false;
}
template<class T>
inline bool chmin(T& x, T y){
    if(x > y){
        x = y;
        return true;
    }
    return false;
}

struct StronglyConnectedComponents{
    using G = vector<vector<int>>;

    G graph;
    G rev;
    int n;
    int scc_sz = 0;
    G scc_graph;

    vector<int> scc_id;
    vector<int> vs;
    vector<bool> visited;

    StronglyConnectedComponents() = default;

    StronglyConnectedComponents(int V) : n(V) {
        graph.resize(n);
        rev.resize(n);
        scc_id.assign(n, -1);
        visited.assign(n, false);
    }

    StronglyConnectedComponents(G& g) : graph(g), n(g.size()) {
        rev.resize(n);
        scc_id.assign(n, -1);
        visited.assign(n, false);
        
        for(int u = 0; u < n; ++u){
            for(int v : graph[u])   rev[v].push_back(u);
        }
    }

    void resize(int V){
        n = V;
        graph.resize(n);
        rev.resize(n);
        scc_id.assign(n, -1);
        visited.assign(n, false);
    }

    void add_edge(int u, int v){
        graph[u].emplace_back(v);
        rev[v].emplace_back(u);
    }

    void dfs(int from){
        visited[from] = true;
        for(int to : graph[from]){
            if(!visited[to])  dfs(to);
        }
        vs.push_back(from);
    }

    void rdfs(int from, int k){
        scc_id[from] = k;
        for(int to : rev[from]){
            if(scc_id[to] == -1)    rdfs(to, k);
        }
    }

    void build(){
        for(int v = 0; v < n; ++v){
            if(!visited[v]) dfs(v);
        }
        reverse(vs.begin(), vs.end());

        for(int v : vs){
            if(scc_id[v] == -1)    rdfs(v, scc_sz++);
        }

        scc_graph.resize(scc_sz);
        for(int v = 0; v < n; ++v){
            scc_graph[scc_id[v]].push_back(v);
        }

        return;
    }

    int size() { return scc_sz; }

    vector<int> get_set(int k) { return scc_graph[k]; }

    int operator[](int v) { return scc_id[v]; }
};

struct TwoSAT {
    StronglyConnectedComponents scc;
    int n;
    vector<int> sat;

    TwoSAT(int V) : n(V) {
        scc.resize(n * 2);
        sat.resize(n);
    }

    // [false] [true]
    void add_edge(int i, bool f, int j, bool g){
        scc.add_edge(i * 2 + (f ? 0 : 1), j * 2 + (g ? 1 : 0));
        scc.add_edge(j * 2 + (g ? 0 : 1), i * 2 + (f ? 1 : 0));
    }

    // sat[v] = true : v = false
    // sat[v] = false : v = true
    bool satisfiable(){
        scc.build();
        for(int i = 0; i < n; ++i){
            if(scc[i * 2] == scc[i * 2 + 1])    return false;
            sat[i] = scc[i * 2] < scc[i * 2 + 1];
        }
        return true;
    }

    vector<int> get_sat() { return sat; }
};

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int N;
    cin >> N;
    if(N > 1000){
        cout << "Impossible\n";
        return 0;
    }
    vector<string> s(N);
    for(int i = 0; i < N; ++i)  cin >> s[i];
    TwoSAT ts(N);
    for(int i = 0; i < N; ++i){
        for(int j = 0; j < i; ++j){
            if(s[i][0] == s[j][0] || s[i].substr(1, 2) == s[j].substr(1, 2)){
                ts.add_edge(i, false, j, false);
            }
            if(s[i][0] == s[j][2] || s[i].substr(1, 2) == s[j].substr(0, 2)){
                ts.add_edge(i, false, j, true);
            }
            if(s[i][2] == s[j][0] || s[i].substr(0, 2) == s[j].substr(1, 2)){
                ts.add_edge(i, true, j, false);
            }
            if(s[i][2] == s[j][2] || s[i].substr(0, 2) == s[j].substr(0, 2)){
                ts.add_edge(i, true, j, true);
            }
        }
    }
    if(!ts.satisfiable()){
        cout << "Impossible\n";
        return 0;
    }
    auto ans = ts.get_sat();
    for(int i = 0; i < N; ++i){
        if(ans[i])  cout << s[i][0] << ' ' << s[i].substr(1, 2) << '\n';
        else    cout << s[i].substr(0, 2) << ' ' << s[i][2] << '\n';
    }

    return 0;
}