#include <cassert>// c
#include <iostream>// io
#include <iomanip>
#include <fstream>
#include <sstream>
#include <vector>// container
#include <map>
#include <unordered_map>
#include <set>
#include <queue>
#include <bitset>
#include <stack>
#include <algorithm>// other
#include <complex>
#include <numeric>
#include <functional>
#include <random>
#include <regex>
using namespace std;

typedef long long ll;typedef unsigned long long ull;typedef long double ld;

#define ALL(c) c.begin(),c.end()
#define IN(l,v,r) (l<=v && v < r)
template<class T> void UNIQUE(T& v){v.erase(unique(ALL(v)),v.end());}
//debug==
#define DUMP(x) cerr << #x <<" = " << (x)
#define LINE() cerr<< " (L" << __LINE__ << ")"

struct range{
	struct Iter{
		int v,step;
		Iter& operator++(){v+=step;return *this;}
		bool operator!=(Iter& itr){return v<itr.v;}
		int& operator*(){return v;}
	};
	Iter i, n;
	range(int i, int n,int step):i({i,step}), n({n,step}){}
	range(int i, int n):range(i,n,1){}
	range(int n):range(0,n){}
	Iter& begin(){return i;}
	Iter& end(){return n;}
};
struct rrange{
	struct Iter{
		int v,step;
		Iter& operator++(){v-=step;return *this;}
		bool operator!=(Iter& itr){return v>itr.v;}
		int& operator*(){return v;}
	};
	Iter i, n;
	rrange(int i, int n,int step):i({i-1,step}), n({n-1,step}){}
	rrange(int i, int n):rrange(i,n,1){}
	rrange(int n) :rrange(0,n){}
	Iter& begin(){return n;}
	Iter& end(){return i;}
};

//input
template<typename T1,typename T2> istream& operator >> (istream& is,pair<T1,T2>& p){return is>>p.first>>p.second;}
template<typename T1> istream& operator >> (istream& is,tuple<T1>& t){return is >> get<0>(t);}
template<typename T1,typename T2> istream& operator >> (istream& is,tuple<T1,T2>& t){return is >> get<0>(t) >> get<1>(t);}
template<typename T1,typename T2,typename T3> istream& operator >> (istream& is,tuple<T1,T2,T3>& t){return is >>get<0>(t)>>get<1>(t)>>get<2>(t);}
template<typename T1,typename T2,typename T3,typename T4> istream& operator >> (istream& is,tuple<T1,T2,T3,T4>& t){return is >> get<0>(t)>>get<1>(t)>>get<2>(t)>>get<3>(t);}
template<typename T> istream& operator >> (istream& is,vector<T>& as){for(int i:range(as.size()))is >>as[i];return is;}
//output
template<typename T> ostream& operator << (ostream& os, const set<T>& ss){for(auto a:ss){if(a!=ss.begin())os<<" "; os<<a;}return os;}
template<typename T1,typename T2> ostream& operator << (ostream& os, const pair<T1,T2>& p){return os<<p.first<<" "<<p.second;}
template<typename K,typename V> ostream& operator << (ostream& os, const map<K,V>& m){bool isF=true;for(auto& p:m){if(!isF)os<<endl;os<<p;isF=false;}return os;}
template<typename T1> ostream& operator << (ostream& os, const tuple<T1>& t){return os << get<0>(t);}
template<typename T1,typename T2> ostream& operator << (ostream& os, const tuple<T1,T2>& t){return os << get<0>(t)<<" "<<get<1>(t);}
template<typename T1,typename T2,typename T3> ostream& operator << (ostream& os, const tuple<T1,T2,T3>& t){return os << get<0>(t)<<" "<<get<1>(t)<<" "<<get<2>(t);}
template<typename T1,typename T2,typename T3,typename T4> ostream& operator << (ostream& os, const tuple<T1,T2,T3,T4>& t){return os << get<0>(t)<<" "<<get<1>(t)<<" "<<get<2>(t)<<" "<<get<3>(t);}
template<typename T> ostream& operator << (ostream& os, const vector<T>& as){for(int i:range(as.size())){if(i!=0)os<<" "; os<<as[i];}return os;}
template<typename T> ostream& operator << (ostream& os, const vector<vector<T>>& as){for(int i:range(as.size())){if(i!=0)os<<endl; os<<as[i];}return os;}

// values
template<typename T> inline T INF(){assert(false);};
template<> inline int INF<int>(){return 1<<28;};
template<> inline ll INF<ll>(){return 1LL<<60;};
template<> inline double INF<double>(){return 1e16;};
template<> inline long double INF<long double>(){return 1e16;};

template<class T> inline T EPS(){assert(false);};
template<> inline int EPS<int>(){return 1;};
template<> inline ll EPS<ll>(){return 1LL;};
template<> inline double EPS<double>(){return 1e-12;};
template<> inline long double EPS<long double>(){return 1e-12;};

// min{2^r | n < 2^r}
template<typename T> inline T upper_pow2(T n){ T res=1;while(res<n)res<<=1;return res;}
// max{d | 2^d  <= n}
template<typename T> inline T msb(T n){ int d=62;while((1LL<<d)>n)d--;return d;}

template<typename T,typename U> T pmod(T v,U M){return (v%M+M)%M;}

class Tarjan{
typedef vector<vector<int>> Graph;
private:
    int N;Graph g;
    vector<int> ord,low;vector<bool> vis;
    stack<int> st;vector<bool> S;
    void dfs(int v,int p,int &oi,int &gi){
        vis[v]=true; ord[v]=low[v]=oi++; st.push(v);S[v]=true;
        for(int to :g[v]){
            if(!vis[to]){
                dfs(to,v,oi,gi);
                low[v]=min(low[v],low[to]);
            }else if(S[to]){
                low[v]=min(low[v],ord[to]);
            }
        }
        if(low[v]!=ord[v])return;
        while(true){
            int w=st.top();cmp[w]=gi;S[w]=false;st.pop();
            if(v==w)break;
        }
        gi++;
    }
public:
vector<int> cmp;
    Tarjan(int N):N(N){
        g=Graph(N);ord=low=cmp=vector<int>(N,-1);vis=S=vector<bool>(N);
    }
    void add_edge(int f,int t){g[f].push_back(t);}
    void scc(){
        int oi=0,gi=0;
        for(int v:range(N))if(!vis[v])dfs(v,-1,oi,gi);
    }
    bool same(int i,int j){return cmp[i]==cmp[j];}
};


class Main{
	public:

	void run(){
		int N;cin >> N;
		if(N > 26*2){
			cout << "Impossible" << endl;
			return;
		}
		vector<string> ss(N);cin >> ss;
		Tarjan scc(2*N);

		for(int i:range(N))for(int bi:range(2))for(int j:range(N))if(i!=j)for(int bj:range(2)){
			bool isdup=false;
			set<string> s;
			if(bi==0){
				isdup |= s.count(ss[i].substr(0,2));
				s.insert(ss[i].substr(0,2));
				isdup |= s.count(ss[i].substr(2,1));
				s.insert(ss[i].substr(2,1));
			}else{
				isdup |= s.count(ss[i].substr(0,1));
				s.insert(ss[i].substr(0,1));
				isdup |= s.count(ss[i].substr(1,2));
				s.insert(ss[i].substr(1,2));
			}
			if(bj==0){
				isdup |= s.count(ss[j].substr(0,2));
				s.insert(ss[j].substr(0,2));
				isdup |= s.count(ss[j].substr(2,1));
				s.insert(ss[j].substr(2,1));
			}else{
				isdup |= s.count(ss[j].substr(0,1));
				s.insert(ss[j].substr(0,1));
				isdup |= s.count(ss[j].substr(1,2));
				s.insert(ss[j].substr(1,2));
			}
			if(isdup){
				// cerr << i+N*bi <<" " << j+N*(1-bj) << endl;
				scc.add_edge(i+N*bi,j+N*(1-bj));
			}
		}
		scc.scc();
		for(int i:range(N)){
			if(scc.same(i,i+N)){
				cout << "Impossible"<<endl;
				return;
			}
		}

		for(int i:range(N)){
			if(scc.cmp[i] > scc.cmp[i+N]){
				cout << ss[i].substr(0,1) <<" " << ss[i].substr(1,2)<<endl;
			}else{
				cout << ss[i].substr(0,2) <<" " << ss[i].substr(2,1)<<endl;
			}
		}
	}
};

int main(){
	cout <<fixed<<setprecision(20);
	cin.tie(0);
	ios::sync_with_stdio(false);
	Main().run();
	return 0;
}