#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
//-------------------------------------------------------

int N;
string S[101010];
int R[101010][4];
int tim[2][65536];

void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>N;
	if(N>52) return _P("Impossible\n");
	FOR(i,N) {
		cin>>S[i];
		R[i][0]=S[i][0];
		R[i][1]=S[i][1]*(int)256+S[i][2];
		R[i][2]=S[i][2];
		R[i][3]=S[i][0]*(int)256+S[i][1];
	}
	
	double start=clock();
	srand(clock());
	x=1;
	while(clock()-start<1.9*CLOCKS_PER_SEC) {
		int A[52]={};
		x++;
		FOR(i,N) {
			A[i]=rand()%2;
			if(A[i]==0) {
				if(tim[0][R[i][0]]==x) goto out;
				if(tim[1][R[i][1]]==x) goto out;
				tim[0][R[i][0]]=x;
				tim[1][R[i][1]]=x;
			}
			else {
				if(tim[0][R[i][2]]==x) goto out;
				if(tim[1][R[i][3]]==x) goto out;
				tim[0][R[i][2]]=x;
				tim[1][R[i][3]]=x;
			}
		}
		
		FOR(i,N) {
			if(A[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;
		out:
			;
	}
	cout<<"Impossible"<<endl;
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n';
	FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	solve(); return 0;
}