#include <bits/stdc++.h>

#define _overload(_1,_2,_3,name,...) name
#define _rep(i,n) _range(i,0,n)
#define _range(i,a,b) for(int i=int(a);i<int(b);++i)
#define rep(...) _overload(__VA_ARGS__,_range,_rep,)(__VA_ARGS__)

#define _rrep(i,n) _rrange(i,n,0)
#define _rrange(i,a,b) for(int i=int(a)-1;i>=int(b);--i)
#define rrep(...) _overload(__VA_ARGS__,_rrange,_rrep,)(__VA_ARGS__)

#define _all(arg) begin(arg),end(arg)
#define uniq(arg) sort(_all(arg)),(arg).erase(unique(_all(arg)),end(arg))
#define getidx(ary,key) lower_bound(_all(ary),key)-begin(ary)
#define clr(a,b) memset((a),(b),sizeof(a))
#define bit(n) (1LL<<(n))
#define popcount(n) (__builtin_popcountll(n))

using namespace std;

template<class T>bool chmax(T &a, const T &b) { return (a<b)?(a=b,1):0;}
template<class T>bool chmin(T &a, const T &b) { return (b<a)?(a=b,1):0;}

using ll=long long;
using R=long double;
const R EPS=1e-9L; // [-1000,1000]->EPS=1e-8 [-10000,10000]->EPS=1e-7
inline int sgn(const R& r){return(r > EPS)-(r < -EPS);}
inline R sq(R x){return sqrt(max(x,0.0L));}

const int dx[8]={1,0,-1,0,1,-1,-1,1};
const int dy[8]={0,1,0,-1,1,1,-1,-1};

// Problem Specific Parameter:
string s[110];
int par[110];


int main(void){
	int n;
	cin >> n;

	if(n>52){
		puts("Impossible");
		return 0;
	}

	rep(i,n) cin >> s[i];
	rep(i,n) par[i]=-1;


	rep(i,n){
		if(par[i]!=-1) continue;
		rep(j,2){
			bool ok=true;
			int tmp[110];
			rep(k,n) tmp[k]=par[k];
			tmp[i]=j;

			queue<int> q;
			q.push(i);

			while(ok and !q.empty()){
				int cur=q.front(); q.pop();
				string one=s[cur].substr(tmp[cur]?2:0,1);
				string two=s[cur].substr(tmp[cur]?0:1,2);
				//cout << cur << " " << one << " " << two << endl;
				rep(k,n){
					if(k==cur) continue;
					int ban=0;
					if(tmp[k]==0) ban|=1;
					if(tmp[k]==1) ban|=2;
					if(s[k].substr(0,1)==one or s[k].substr(1,2)==two) ban|=2;
					if(s[k].substr(0,2)==two or s[k].substr(2,1)==one) ban|=1;
					
					if(ban==3){
						ok=false;
						break;
					}

					if(ban!=0 and tmp[k]==-1){
						if(ban==2) tmp[k]=1;
						if(ban==1) tmp[k]=0;
						q.push(k);
					}
				}
			}

			if(ok){
				rep(k,n) par[k]=tmp[k];
				break;
			}
			par[i]=-1;
		}

		if(par[i]==-1){
			puts("Impossible");
			return 0;
		}
	}

	rep(i,n){
		if(par[i]==0)
			cout << s[i].substr(0,1) << " " << s[i].substr(1,2) << endl;
		else
			cout << s[i].substr(0,2) << " " << s[i].substr(2,1) << endl;
	}

	return 0;
}