#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define vtpl(x,y,z) vector<tuple<x,y,z>>
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9+10;
const ll INF=4e18;
const ll dy[9]={0,1,-1,0,1,1,-1,-1,0};
const ll dx[9]={1,0,0,-1,1,-1,1,-1,0};
template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

struct SCC{//多重辺、自己辺ok
    int n,k=0;
    vector<vector<int>> g,rg;
    vector<vector<long long>> ret;
    vector<int> vs,cmp;
    vector<bool> used;
    SCC(int _n){
        n=_n;
        g=vector<vector<int>>(n);rg=g;
        cmp=vector<int>(n);used=vector<bool>(n);
    }
    void add_edge(int f, int t){
        g[f].push_back(t);rg[t].push_back(f);
    }
    int init(){
        rep(i,n)if(!used[i])dfs(i);
        used=vector<bool>(n,false);
        per(i,n){
            if(!used[vs[i]]){
                rdfs(vs[i],k);
                k++;
            }
        }
        return k;
    }
    vector<vector<ll>> build(){//自己辺はないが多重辺あり
        ret.resize(k);
        rep(i,n){
            for(auto to:g[i]){
                if(cmp[i]==cmp[to])continue;
                ret[cmp[i]].push_back(cmp[to]);
            }
        }
        return ret;
    }
    private:
    void dfs(int v){
        used[v]=true;
        rep(i,g[v].size()){
            if(!used[g[v][i]])dfs(g[v][i]);
        }
        vs.push_back(v);
    }
    void rdfs(int v, int k){
        used[v]=true;cmp[v]=k;
        rep(i,rg[v].size()){
            if(!used[rg[v][i]]){
                rdfs(rg[v][i],k);
            }
        }
    }
};

struct twoSAT{
    vector<bool> ans;
    twoSAT(int _n):n(_n),graph(2*_n),ans(_n){}
    void add_edge(int i,bool x,int j,bool y){//( i V j ),falseは否定
        if(!x)i+=n;if(!y)j+=n;
        graph.add_edge((i+n)%(2*n),j);
        graph.add_edge((j+n)%(2*n),i);
    }
    bool exe(){
        graph.init();
        rep(i,n){
            if(graph.cmp[i]==graph.cmp[i+n])return false;
            else if(graph.cmp[i]>graph.cmp[i+n])ans[i]=true;
            else ans[i]=false;
        }
        return true;
    }
    private:
    int n;SCC graph;
};

int main(){
    ll n;cin >> n;
    if(n>52){
        cout << "Impossible" << endl;return 0;
    }
    vector<string> s(n);rep(i,n)cin >> s[i];
    twoSAT ts(n);
    rep(i,n){
        rep(j,i){
            if(s[i].substr(0,1)==s[j].substr(0,1)||s[i].substr(1,2)==s[j].substr(1,2)){
                ts.add_edge(i,true,j,true);
            }
            if(s[i].substr(0,1)==s[j].substr(2,1)||s[i].substr(1,2)==s[j].substr(0,2)){
                ts.add_edge(i,true,j,false);
            }
            if(s[i].substr(2,1)==s[j].substr(0,1)||s[i].substr(0,2)==s[j].substr(1,2)){
                ts.add_edge(i,false,j,true);
            }
            if(s[i].substr(2,1)==s[j].substr(2,1)||s[i].substr(0,2)==s[j].substr(0,2)){
                ts.add_edge(i,false,j,false);
            }
        }
    }
    if(!ts.exe())cout << "Impossible" << endl;
    else{
        rep(i,n){
            if(ts.ans[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;
        }
    }

}