#include <iostream>
#include <algorithm>
#include <complex>
#include <utility>
#include <vector>
#include <string>
#include <queue>
#include <tuple>
#include <cmath>
#include <bitset>
#include <cctype>
#include <set>
#include <map>
#include <numeric>
#include <functional>
#define _overload3(_1,_2,_3,name,...) name
#define _rep(i,n) repi(i,0,n)
#define repi(i,a,b) for(ll i=ll(a);i<ll(b);++i)
#define rep(...) _overload3(__VA_ARGS__,repi,_rep,)(__VA_ARGS__)
#define all(x) (x).begin(),(x).end()
#define PRINT(V) cout << V << "\n"
#define SORT(V) sort((V).begin(),(V).end())
#define RSORT(V) sort((V).rbegin(), (V).rend())
using namespace std;
using ll = long long;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
inline void Yes(bool condition){ if(condition) PRINT("Yes"); else PRINT("No"); }
template<class itr> void cins(itr first,itr last){
    for (auto i = first;i != last;i++){
        cin >> (*i);
    }
}
template<class itr> void array_output(itr start,itr goal){
    string ans = "",k = " ";
    for (auto i = start;i != goal;i++) ans += to_string(*i)+k;
    if (!ans.empty()) ans.pop_back();
    PRINT(ans);
}
ll gcd(ll a, ll b) {
    return a ? gcd(b%a,a) : b;
}
const ll INF = 1e16;
const ll MOD = 1000000007;
typedef pair<ll,ll> P;
const ll MAX = 200005;
constexpr ll nx[8] = {1,0,-1,0,-1,-1,1,1};
constexpr ll ny[8] = {0,1,0,-1,-1,1,-1,1};
class StronglyConnectedComponents{
    private:
        int siz;
        vector<vector<int>> g,rg;
        vector<int> vs,cmp;
        vector<bool> done;
    public:
        StronglyConnectedComponents(int n){
            siz = n;
            g.resize(n);
            rg.resize(n);
            cmp.resize(n);
        }
        void add_edge(int from,int to){
            g[from].push_back(to);
            rg[to].push_back(from);
        }
        void dfs(int v){
            done[v] = true;
            for(int u:g[v]){
                if (!done[u]) dfs(u);
            }
            vs.push_back(v);
        }
        void rdfs(int v,int k){
            done[v] = true;
            cmp[v] = k;
            for(int u:rg[v]){
                if (!done[u]) rdfs(u,k);
            }
        }
        int scc(){
            done.assign(siz,false);
            rep(v,siz) if (!done[v]) dfs(v);
            done.assign(siz,false);
            int k = 0;
            for (int v = siz-1;v >= 0;v--) if (!done[vs[v]]) rdfs(vs[v],k++);
            return k;
        }
        int operator[](int k){
            return cmp[k];
        }
};
int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll n;
    cin >> n;
    if (n > 3000){
        PRINT("Impossible");
        return 0;
    }
    vector<string> u(n);
    cins(all(u));
    StronglyConnectedComponents g(2*n);
    rep(i,n-1){
        rep(j,i+1,n){
            string s = u[i],t = u[j];
            if (s[0] == t[0] || s.substr(1,2) == t.substr(1,2)){
                g.add_edge(i,j+n);
                g.add_edge(j,i+n);
            }
            if (s[0] == t[2] || s.substr(1,2) == t.substr(0,2)){
                g.add_edge(i,j);
                g.add_edge(j+n,i+n);
            }
            if (s[2] == t[0] || s.substr(0,2) == t.substr(1,2)){
                g.add_edge(j,i);
                g.add_edge(i+n,j+n);
            }
            if (s[2] == t[2] || s.substr(0,2) == t.substr(0,2)){
                g.add_edge(i+n,j);
                g.add_edge(j+n,i);
            }
        }
    }
    g.scc();
    rep(i,n){
        if (g[i] == g[i+n]){
            PRINT("Impossible");
            return 0;
        }
    }
    rep(i,n){
        if (g[i] > g[i+n]){
            cout << u[i][0] << " " << u[i].substr(1,2) << '\n';
        }
        else{
            cout << u[i].substr(0,2) << " " << u[i][2] << '\n';
        }
    }
}