// 最悪計算量は確実にTLEするレベルだが
// 実際は問題ない(と思いたい)
#include<iostream>
#include<vector>
using namespace std;
#define inRange(x,a,b) (a <= x && x <= b)

int main(){
    int n;
    cin >> n;
    if(n > 26){
        cout << "Impossible" << endl;
        return 0;
    }
    auto enc = [](string &s)->int{
        int ret = 0;
        for(int i = s.length()-1; i >= 0; i--){
            ret *= 52;
            if(inRange(s[i],'a','z')){
                ret += s[i]-'a';
            }else{
                ret += 26 + s[i]-'A';
            }
        }
        if(s.length() == 2) ret += 52;
        return ret;
    };
    auto f = [](int i, string &s)->pair<string,string>{
        if(i == 0)  return {s.substr(0,1), s.substr(1,2)};
        else        return {s.substr(0,2), s.substr(2,1)};
    };
    vector<string> v(n);
    for(int i = 0; i < n; i++)  cin >> v[i];
    bool used[3000] = {};
    for(int i = 0; i < 1<<n; i++){
        bool ng = false;
        for(int j = 0; j < n; j++){
            pair<string,string> p = f((i>>j)&1, v[j]);
            int a = enc(p.first), b = enc(p.second);
            if(used[a] || used[b]){
                while(--j >= 0){
                    p = f((i>>j)&1, v[j]);
                    int a = enc(p.first), b = enc(p.second);
                    used[a] = used[b] = false;
                }
                ng = true;
                break;
            }else{
                used[a] = used[b] = true;
            }
        }
        if(ng)  continue;

        // ok!
        for(int j = 0; j < n; j++){
            pair<string,string> p = f((i>>j)&1, v[j]);
            cout << p.first << " " << p.second << endl;
        }
        return 0;
    }
    cout << "Impossible" << endl;
    return 0;
}