#include <bits/stdc++.h>
#include <sys/time.h>
using namespace std;

#define rep(i,n) for(long long i = 0; i < (long long)(n); i++)
#define repi(i,a,b) for(long long i = (long long)(a); i < (long long)(b); i++)
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define fi first
#define se second
#define mt make_tuple
#define mp make_pair
#define ZERO(a) memset(a,0,sizeof(a))
template<class T1, class T2> bool chmin(T1 &a, T2 b) { return b < a && (a = b, true); }
template<class T1, class T2> bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
#define exists find_if
#define forall all_of

using ll = long long; using vll = vector<ll>; using vvll = vector<vll>; using P = pair<ll, ll>;
using ld = long double;  using vld = vector<ld>; 
using vi = vector<int>; using vvi = vector<vi>; vll conv(vi& v) { vll r(v.size()); rep(i, v.size()) r[i] = v[i]; return r; }

inline void input(int &v){ v=0;char c=0;int p=1; while(c<'0' || c>'9'){if(c=='-')p=-1;c=getchar();} while(c>='0' && c<='9'){v=(v<<3)+(v<<1)+c-'0';c=getchar();} v*=p; }
template <typename T, typename U> ostream &operator<<(ostream &o, const pair<T, U> &v) {  o << "(" << v.first << ", " << v.second << ")"; return o; }
template<size_t...> struct seq{}; template<size_t N, size_t... Is> struct gen_seq : gen_seq<N-1, N-1, Is...>{}; template<size_t... Is> struct gen_seq<0, Is...> : seq<Is...>{};
template<class Ch, class Tr, class Tuple, size_t... Is>
void print_tuple(basic_ostream<Ch,Tr>& os, Tuple const& t, seq<Is...>){ using s = int[]; (void)s{0, (void(os << (Is == 0? "" : ", ") << get<Is>(t)), 0)...}; }
template<class Ch, class Tr, class... Args> 
auto operator<<(basic_ostream<Ch, Tr>& os, tuple<Args...> const& t) -> basic_ostream<Ch, Tr>& { os << "("; print_tuple(os, t, gen_seq<sizeof...(Args)>()); return os << ")"; }
ostream &operator<<(ostream &o, const vvll &v) { rep(i, v.size()) { rep(j, v[i].size()) o << v[i][j] << " "; o << endl; } return o; }
template <typename T> ostream &operator<<(ostream &o, const vector<T> &v) { o << '['; rep(i, v.size()) o << v[i] << (i != v.size()-1 ? ", " : ""); o << "]";  return o; }
template <typename T>  ostream &operator<<(ostream &o, const set<T> &m) { o << '['; for (auto it = m.begin(); it != m.end(); it++) o << *it << (next(it) != m.end() ? ", " : ""); o << "]";  return o; }
template <typename T>  ostream &operator<<(ostream &o, const unordered_set<T> &m) { o << '['; for (auto it = m.begin(); it != m.end(); it++) o << *it << (next(it) != m.end() ? ", " : ""); o << "]";  return o; }
template <typename T, typename U>  ostream &operator<<(ostream &o, const map<T, U> &m) { o << '['; for (auto it = m.begin(); it != m.end(); it++) o << *it << (next(it) != m.end() ? ", " : ""); o << "]";  return o; }
template <typename T, typename U, typename V>  ostream &operator<<(ostream &o, const unordered_map<T, U, V> &m) { o << '['; for (auto it = m.begin(); it != m.end(); it++) o << *it; o << "]";  return o; }
vector<int> range(const int x, const int y) { vector<int> v(y - x + 1); iota(v.begin(), v.end(), x); return v; }
template <typename T> istream& operator>>(istream& i, vector<T>& o) { rep(j, o.size()) i >> o[j]; return i;}
string bits_to_string(ll input, ll n=64) { string s; rep(i, n) s += '0' + !!(input & (1ll << i)); reverse(all(s)); return s; }
template <typename T> ostream &operator<<(ostream &o, const priority_queue<T> &v) { auto tmp = v; while (tmp.size()) { auto x = tmp.top(); tmp.pop(); o << x << " ";} o << endl; return o; }

template <typename T> unordered_map<T, ll> counter(vector<T> vec){unordered_map<T, ll> ret; for (auto&& x : vec) ret[x]++; return ret;};
string substr(string s, P x) {return s.substr(x.fi, x.se - x.fi); }
void vizGraph(vvll& g, int mode = 0, string filename = "out.png") { ofstream ofs("./out.dot"); ofs << "digraph graph_name {" << endl; set<P> memo; rep(i, g.size())  rep(j, g[i].size()) { if (mode && (memo.count(P(i, g[i][j])) || memo.count(P(g[i][j], i)))) continue; memo.insert(P(i, g[i][j])); ofs << "    " << i << " -> " << g[i][j] << (mode ? " [arrowhead = none]" : "")<< endl;  } ofs << "}" << endl; ofs.close(); system(((string)"dot -T png out.dot >" + filename).c_str()); }

size_t random_seed; namespace std { using argument_type = P; template<> struct hash<argument_type> { size_t operator()(argument_type const& x) const { size_t seed = random_seed; seed ^= hash<ll>{}(x.fi); seed ^= (hash<ll>{}(x.se) << 1); return seed; } }; }; // hash for various class
namespace myhash{ const int Bsizes[]={3,9,13,17,21,25,29,33,37,41,45,49,53,57,61,65,69,73,77,81}; const int xor_nums[]={0x100007d1,0x5ff049c9,0x14560859,0x07087fef,0x3e277d49,0x4dba1f17,0x709c5988,0x05904258,0x1aa71872,0x238819b3,0x7b002bb7,0x1cf91302,0x0012290a,0x1083576b,0x76473e49,0x3d86295b,0x20536814,0x08634f4d,0x115405e8,0x0e6359f2}; const int hash_key=xor_nums[rand()%20]; const int mod_key=xor_nums[rand()%20]; template <typename T> struct myhash{ std::size_t operator()(const T& val) const { return (hash<T>{}(val)%mod_key)^hash_key; } }; };
template <typename T> class uset:public std::unordered_set<T,myhash::myhash<T>> { using SET=std::unordered_set<T,myhash::myhash<T>>; public: uset():SET(){SET::rehash(myhash::Bsizes[rand()%20]);} };
uint32_t randxor() { static uint32_t x=1+(uint32_t)random_seed,y=362436069,z=521288629,w=88675123; uint32_t t; t=(x^(x<<11));x=y;y=z;z=w; return( w=(w^(w>>19))^(t^(t>>8)) ); }
struct timeval start; double sec() { struct timeval tv; gettimeofday(&tv, NULL); return (tv.tv_sec - start.tv_sec) + (tv.tv_usec - start.tv_usec) * 1e-6; }
struct init_{init_(){ gettimeofday(&start, NULL); ios::sync_with_stdio(false); cin.tie(0); struct timeval myTime; struct tm *time_st; gettimeofday(&myTime, NULL); time_st = localtime(&myTime.tv_sec); srand(myTime.tv_usec); random_seed = RAND_MAX / 2 + rand() / 2; }} init__;
#define rand randxor

static const double EPS = 1e-14;
static const long long INF = 1e18;
static const long long mo = 1e9+7;
#define ldout fixed << setprecision(40) 



class SAT {
public:
    ll n;
    // v in [0, n)      x_v = T
    // v in [n, 2n)     x_v = F
    vvll g;
    vvll g_rev;
    vector<bool> ret;
    SAT (ll n_) : n(n_), g(n*2), g_rev(n*2) {
    }
    inline ll node(ll t) {
        return (t > 0 ? t-1 : n+(-t)-1);
    }
    // and (sign(t1) x_|t1| or sign(t2) t2)を論理式に加える。
    // ただし、sign(t)はt>0で何もなし、t<0でnot
    //
    // 1 <= |t1| <= n
    // 1 <= |t2| <= n
    void addClause(ll t1, ll t2) {
        assert(1 <= abs(t1) && abs(t1) <= n);
        assert(1 <= abs(t2) && abs(t2) <= n);
        g[node(-t1)].pb(node(t2));
        g[node(-t2)].pb(node(t1));
        g_rev[node(t1)].pb(node(-t1));
        g_rev[node(t2)].pb(node(-t2));
    }

    // 従属可能で1を出力
    bool solve(void) {
        vll id;
        vector<bool> visited(g.size());
        rep(i, g.size()) {
            function<void(ll)> dfs1 = [&](ll v) {
                if (visited[v]) return;
                visited[v] = true;
                for (auto x : g[v]) {
                    dfs1(x);
                }
                id.pb(v);
            };
            dfs1(i);
        }

        fill(all(visited), false);
        vll color(g.size(), -1);
        for (int i = id.size() - 1; i >= 0; i--) {
            function<void(ll)> dfs2 = [&](ll v) {
                if (visited[v]) return;
                visited[v] = true;
                for (auto x : g[v]) {
                    dfs2(x);
                }
                color[v] = i;
            };
            dfs2(i);
        }
        
        ret.resize(0);
        rep(v, n) if (color[v] == color[v+n]) return 1;
        ret.resize(n);
        rep(i, n) ret[i] = color[i] > color[i+n];
        return 0;
    }
    vector<bool> getAnswer(void) {
        return ret;
    }
    void print_answer(void) {
        if (ret.size()) {
            cout << "SAT : ";
            rep(i, n) 
                cout << ret[i] << " ";
            cout << endl;
        } else {
            cout << "UNSAT" << endl;
        }
    }
};

// 2-SATソルバ
//
// 使い方
// SAT sat(n);
// x_1, ... x_nの変数が確保される。
// addClouseなどは1-index!! 理由は、not Aを-Aとして表現するから！
//
// sat.addClause({i, j, h}) 
//      x_iもしくはx_jもしくはx_hが成立する
//      addClause({x_i, x_j})など、2つでもOK
//      x_iは負だと、「x_iが成立しない」という意味になる
//
// sat.solve
//      0ならSAT, 1ならUNSAT, 2ならエラーなり解を見つけられなかったり
//      SATなら副作用でsolver.assigns[i]にx_{i+1}の割当結果が得られる
//      注意すべきなのは、0がtrueで1がfalseであること


int main(void) {
    ll n; cin >> n;
    if (n > 26*2) return cout << "Impossible" << endl, 0;

    vector<string> u(n); cin >> u;
    SAT sat(n);

    map<string, vll> memo;
    rep(i, n) {
        memo[u[i].substr(0, 1)].pb(i+1);
        memo[u[i].substr(1, 2)].pb(i+1);
        memo[u[i].substr(0, 2)].pb(-i-1);
        memo[u[i].substr(2, 1)].pb(-i-1);
    }

    for (auto&& x : memo) {
        auto&& v = x.se;
        for (auto i : v) for (auto j : v) if (i != j) {
            sat.addClause(-i, -j);
        }
    }

    ll ret = sat.solve();
    if (ret == 0) {
        rep(i, n) {
            if (sat.ret[i] != 0) 
                cout << u[i].substr(0, 1) << " " << u[i].substr(1, 2) << endl;
            else 
                cout << u[i].substr(0, 2) << " " << u[i].substr(2, 1) << endl;
        }
    } else {
        cout << "Impossible" << endl;
    }

    return 0;
}